Sorry, but when it comes to Fr. Hesse's ordination, they and he did know better, better than you and better than me - that much is certain.
How do they know better? The facts are the facts. An "investigation" can't change the facts -- you obviously have swallowed the new-sspx's lie that it can.
a. The new rite of ordination was changed. Fact.
b. The new rite's changes cause doubt. Fact.
c. "Fr" Hesse said he was ordained in the new rite. He does not dispute this. Fact.
d. We know what the new rite says, because it's a public docuмent. Fact.
e. Ergo, "Fr" Hesse's ordination is doubtful, because it was done using a doubtful rite. Fact.
I am not defending the SSPX's policy,
If you keep arguing that they "know better" then you absolutely are defending their policy. Because they don't know better.
a. New rite is a public docuмent.
b. New rite does not have variations; there is only 1 way to say the new rite of ordination.
c. Fr Hesse said he was ordained in the new rite. No variations.
d. Ergo, we all know EXACTLY how the rite was performed, what was said, etc. There's "nothing else" to know.
There is no mystery to be solved. There is no investigation needed to uncover "secret" facts. The rite is known, it was used. No one disputes this. Those are the only facts that matter.
but the SSPX *STILL* believe that NO ordinations are valid when done by the book.
Then they are the indult. Because no Traditionalist, going back to the early 1970s, trusted the new rites. That's why Trads started their own seminaries.
IF, "when done by the book" the new rite ordinations are valid, then they are just as valid now as they were then

Not hardly. The problem with the new rite of ordination is two-fold:
1. New rite is doubtful.
2. The new rite for bishops is also doubtful.
So you have a doubtful bishop ordaining a doubtful priest. 2 doubts.
In the 70s/80s, there were *some* old rite/true bishops. If a true bishop ordains in the new rite, that is still doubtful, but it's only 1 doubt. Slightly less doubt, but it still exists.
I agree that WE don't know - but that's *not* the point. The point is that the SSPX SAY that they *do* know.
This is the beginning of their contradiction and lies. They say: All new rites are valid.
As such, they are adhering to what the Church has always done by investigating each NO priest's ordination that comes to them. It's not complicated.

The Church only did an investigation WITH DOUBTFUL ORDERS.
So the new-sspx wants us all to believe that "new rites are valid" ...but also...we will investigate. If you do an investigation, YOU ARE ADMITTING THERE IS DOUBT.
Ergo, their contradiction that "new rites are valid" is bogus.