Jarvis' biography is the best academic work on Msgr. Thuc. Yes, the author has biases that come through in the text, but an educated adult should be able to navigate biases.
I saw this intro on Amazon (the very first sentence) ... not sure who wrote it.
Sedevacantism, American Catholicism’s only homegrown "new religious movement" (NRM), argues that the Catholic Church has sunk into heresy at the hands of false popes.
That's not even close to true, in general, but even about sedevacantism. There were early Sedevacantists all over the world, particularly in Mexico, but elsewhere as well.
Not to mention that, no, we do not hold that "the Catholic Church" has sunk into heresy ... that's precisely the point of SVism.
If Jarvis wrote this, then he's discredited in the very first sentence.