I think Michaels' contract was for guaranteed money.
But, you're right - he should have at least been a little more appreciative/respectful of sharing the ring with Hulkster.
I wonder if it was more out of respect.
Yeah, his selling was over the top, but so was Terry Funk's a lot of the time, and it was under the pretense of making the opponent look good & enhancing the match overall.
I have my doubts that HBK would extend such a courtesy.
But, if you watch, it wasn't all tacky overselling.
He went extra high for the high-spots, low-spots, and all spots.
Of course, with Hogan being well past his prime, it may have also been an attempt on Shawn's part to easily upstage the "immortal one," and showcasing how much better a worker Shawn is.