This is just my non-medical opinion based on pictures, but new pictures of Gustafsson's injury on Friday show that it was significantly healed. I am relying on an image from his interview on Fuel. Clearly, there is a scar, but Gustafsson says the stitches had been removed two days previous ( I wish the interviewer had asked whether the stitches had been removed when the SMMAF doctors examined him the second time). Thus, the wound was closed, which must be the first criteria for determining whether a fighter will be approved to fight. Obviously, it would make quite a difference if Gustafsson was examined with stitches.
I am assuming the stitches had been removed when Gus was ruled out. As Luke Thomas pointed out, there appears to be no set criteria or guidelines for ruling a fighter in or out for an un-open wound. One can surmise that the doctors look for swelling, soreness, thin scar tissue, and other indicia of a not fully healed wound, which could be reopened with little force. That would be reasonable and I suspect that is why Gustafsson was ruled out. I have read and heard from Swedes that the SMMAF must exercise an abundance of caution. Indeed, the SMMAF rules require doctors examining fighters during a contest to make their decisions based on "worst case scenario." In other words, assume the fighter will get hit where the injury exists.
But I wonder whether Gustafsson would have been approved had he not disclosed the injury in the first place. I realize that may have been impossible given he went to the emergency room, but, hey, in the movies there is always some quack willing to stitch someone up with no questions asked. Actually, not just in the movies. I believe, based on how Gustafsson's injury healed, that had he not reported it and merely showed up on Friday after the stitches had been removed he would have been approved. It would have required some deception (non-disclosure), but my argument is not that he should have deceived anyone. Rather, it is that had he been examined without knowledge of the nature of the injury and the need for stitches, he would have been allowed to fight.