Plus, I'd be more concerned if he's spending more than 20% of his take-home on PITI than I would be about the value of the home. In other words, a $100K salary and a $600K home with a $2500/month mortgage would raise a serious red flag.
I once had a pastor who was independently wealthy, had a huge house, and put his entire paycheck in the plate every month. The only reason I know he did that is because my father was the treasurer.
If I was worth $10 million and in full-time ministry, I might stay in my $170K home, but I'd have a maid, a yard man, a chef, some more reliable baby sitters, and a newer car. Would I be judged for buying back more time for ministry by employing 4 people? Probably - that's how it goes.