Why would any Catholic wish to allow even the possibility that the Flood was NOT geographically worldwide?  What would be the motivation?  Why would God only flood part of the Earth?

Simple.  kowtowing to the god of modern “science”.  CE pretty much admits that it’s the reason for the prevarication.

Why would any Catholic wish to allow even the possibility that the Flood was NOT geographically worldwide?  What would be the motivation?  Why would God only flood part of the Earth?

It's just as Matto noted earlier in the thread. People have been completely indoctrinated by the evolutionist "old earth" hypothesis that they actually err on the side of it rather than Sacred Scripture.

Why would any Catholic wish to allow even the possibility that the Flood was NOT geographically worldwide?  What would be the motivation?

Consider a different question: Why would any Catholic wish to allow the possibility that there won't be dogs in heaven?

The answer should be that the Church doesn't teach that dogs do or don't go to heaven. Sure, one can muster some arguments on either side, including some passages from Scripture, but they're not definitive. The point is the Church (as far as I know) does not propose a belief about dogs either way as a matter of faith.

And if you disagree, the proper argument is to show the Church teaches one way or another.

You actually didn't quote them in this thread, but in this one:
https://www.cathinfo.com/fighting-errors-in-the-modern-world/does-neo-sspx-hold-that-noah's-flood-didn't-cover-the-entire-world/msg748677/#msg748677

Thanks, VT! Let me put that here for Stanley to read.
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Stanley, your question makes little sense. It's like saying, "Does the Church say we have an obligation to accept Trent's decree on justification? I don't see where it says we have to believe that." We are obliged to accept every word of the Council of Trent. In the same way, we are obliged to accept every word of the Bible. In practical terms, the Bible is like one huge, long, 1200-word, three-millennium ex cathedra definition, except even more so, because an ex cathedra definition is usually only a brief statement surrounded by lots of explanatory text that is not in itsel de fide, whereas every word of the Bible is de fide.
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So to say, "I don't see where the Church said we have to believe the flood covered the entire face of the earth, so I can believe it didn't, since it doesn't say I can't," makes about as much as saying, "I don't see where the Church has defined that Abraham's name was Abraham and not Jack Black, so I think I will believe that Abraham's name was actually Jack Black, since the Church hasn't told me that I can't."
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To reiterate, you are obliged to accept with divine and Catholic Faith every word of the Bible including the following:
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He said to Noe: The end of all flesh is come before me, the earth is filled with iniquity through them, and I will destroy them with the earth. Make thee an ark of timber planks

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Behold I will bring the waters of a great flood upon the earth, to destroy all flesh, wherein is the breath of life, under heaven. All things that are in the earth shall be consumed..

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For yet a while, and after seven days, I will rain upon the earth forty days and forty nights; and I will destroy every substance that I have made, from the face of the earth.

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And he was six hundred years old, when the waters of the flood overflowed the earth.And the flood was forty days upon the earth, and the waters increased, and lifted up the ark on high from the earth. For they overflowed exceedingly: and filled all on the face of the earth: and the ark was carried upon the waters. And the waters prevailed beyond measure upon the earth: and all the high mountains under the whole heaven were covered. The water was fifteen cubits higher than the mountains which it covered. . and Noe only remained, and they that were with him in the ark. And the waters prevailed upon the earth a hundred and fifty days.

The universal flood seems to me to lend credence to Flat Earth theory as does the firmament.

On a flat earth water would run off the edge, no?  

Whaaaa???? Dogs in heaven??
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Now this conversation is starting to make a lot more sense. You seem to be clueless about what the Catholic Church actually teaches about anything.

I have to do something to get points across. Go ahead and have a laugh - that's intentional - but you might consider holding back on your accusations of "clueless". Dogs in heaven or not is speculative theology, but there are arguments on various positions (there are at least 3 main positions).

Some here are taking for granted that certain things are required of the faith. OK, go ahead, prove it.

Or don't you mind adding things to the deposit of faith?

Let's try another one: is "day" in Genesis 24 hours or an indefinite period of time that may be long?

Most here are probably aware the biblical commission allowed either view. So the Church does not require belief in either.

If you were living before the biblical commission answered, would you have held that a "day" has to be "24 hours" and anything else is "modernism"? That is basically a rhetorical question. I'm not expecting a serious answer.

I have met "traditional catholics" who rejected the biblical commission decision as "modernist" because "it's obvious from Scripture and Tradition" that a Genesis day is "24 hours". They simply reject a church decision under Pope St. Pius X because they - with no theology training or credentials - disagree with it. It boggles my mind and makes me wonder where their motive for faith lies.