I don't know that I've read it, but Krang was a heel long before that.
Depends on the story the creators handling him wanted to tell, really.If he didn't see Namor as an enemy before, would you think he would find a peace with Namor or continue to undermine him?
But with a name like "Krang," I don't see him destined for heroism, I gotta say.
kdb