Maybe he can sell it or maybe not. What worked before may not work now. You know he has four mortgages? He must have confided in you, when (as very recently) it was a sign of coolness to be able to qualify for huge mortgages.
I am not sure what realtors will do if they have to pay mortgages. There are almost no sales now in my area in the northeast.
As it happens I have been house shopping recently. And a good half of the realtors are acting very tough, pretending there are competing bids on a property when there aren't, etc. You have to just assume there's never a competing bid these days, and it's possible you would lose a property that way, but all 3 (!) times we just said "ok, let them have it" and the realtor came back to us eventually with some story about how the other bid didn't really materialize. As it happens, we have backed away from further interest on all 3 houses, and they are all still for sale.
There's one other house where our bid was rejected, then later it seems a higher legit bid apparently came along and was accepted. Good for them! But in this case the realtor was very respectable, actually I wouldn't mind working with her after this experience.
Maybe the others think that the only way to sell a house these days is with trickery. If they do, who am I to say they're wrong? I doubt I would be a very successful realtor, so I can't tell them their business.