You mention he is always saying he is going to get laid off - yet he has apparently done nothing about it. Any lawyer worth their salt will latch onto this; that being laid off would NOT be a surprise and thus he had opportunity - and responsibility - to take steps to rectify that by at least looking for other employment.

I was in a similar position. My ex tried to get the chid support lowered as he found himself out of work. My lawyer and I pointed to the fact that he was in a contracted position - that he had then had 3yrs notice to make plans. They immediately withdrew their motion.

I see your case as similar. He knows his job is apparently tenuous. Unless he himself was able to prove MI, quitting it would not improve his case.