This is the thing - it all comes down to perspective. Effectively he's been quickly KOd twice for vast amounts of money. A quick KO loss is probably better for your health than winning a five round war. He sustained no damage leading up to both knockouts.Depends on how well he was financially compensated.
I agree that he probably cut his title reign short by a year or two but I bet the money that he got for the Islam rematch is much, much more than he would have been paid for a regular fight.
Not saying it was the right decision. Just that he might've come out with more money and less damage in the long run