Father Wathen's views about the NOM and EENS dogma are not highly regarded by SSPX.

But Fr. Wathen's views on EENS and the NOM are in fact right opinion, whilst the views of the SSPX on these matters are woefully deficient.

I was once for a walk with Msgr. Williamson after dinner (late autumn 1989) and he broached to subject of the validity of the NOM. He did not seem pleased that I did not follow the SSPX line on the matter. I avoided discussing further, namely that my opinion hangs on the doubtful validity of NO episcopal consecrations. I think I redirected to conversation to Tannhäuser vs. the Ring Cycle.

MaterDominici, is that you? 

Matthew, will you stand for this?

Seriously, though, ex-seminarians take much of what they learned into whatever vocation they end up in, both in terms of their knowledge of the faith and spiritual formation, and none of it is wasted.  To paraphrase Evelyn Waugh, if ex-seminarians are lame, imagine how lame they (we) would be had we not gone to seminary at all.

Waugh:

Yes, perhaps it helps them to be better men.

There might also be the possibility that priestly knowledge can be wielded incorrectly by someone who, in fact, is not a priest.

I don't know. My general experience is that it has something to do with some kind of autism.

Could be wrong. But you meet five, ten, twenty over the years and you see patterns....