May be coincidental.
He left about the time that his CO2 hypothesis was demonstrated to be wrong, and that it was H20. He had a lot invested in that, had advocated strongly. In one fell swoop one of the rovers or orbiters developed information which proved it was water.
While he had adequate information for his hypothesis, it was not foolish or crackpot, he may have been embarrassed. And maybe not.
He also was dealing with cancer either in himself or a family member and I think he got remarried. I may have those issues wrong or in the wrong time period.