This is a long held opinion. There may be truth in it, but it is very hard to test.
How many bears, when hurt, will avoid the thing which hurt them? We know this happens in some cases. The bear was willing to attack a human at the beginning. Is it more or less likely to attack a human after being severely hurt by a human?
We know when wounded bears attack. We don't know when they avoid. So there is considerable selection bias.
It probably depends on the wound and the individual and the sex of the bear. And whether or not the wound hampered the bear’s normal hunting capability?
Just a guess.