How are there still people in the SSPX who think a personal prelature is a good idea in these times?
It's insanity.
The fact is, Rome is still Modernist through-and-through. Even if you THINK you're getting away with a decent Tridentine Mass, traditional parish, it's only temporary.
Water and oil don't mix. You can only have an "aberration" or "exception" for so long. Then it must return to normal. In this case, to Novus Ordo Modernist heresy.
Given enough time/patience, the fundamentals
always prevail.