Fighting Volk made sense for islam, and he chose volk at least one of the times they fought, which is why people are pointing out the hypocrisy of islam now saying that fighting featherweights does nothing for his career. That said, I think it's because Islam saw the fans' somewhat sour reactions to the second Volk fight and learned from that, so he now believes that beating featherweights does nothing for his career because fandom downplayed that win. He was certainly interested in it before, though.
Frankly, I don't blame the guy for not wanting to fight Featherweights anymore. Not only did a featherweight give him his toughest fight, but fans also belittle the fights because it was a featherweight. Lose lose scenario, but still, one that islam walked himself into.
If gamrot was stuck in the limbo of "back up fighter, but only in the last few days of a fight cancellation", then Islam wouldn't have been able to chose gamrot as an option at all when charles pulled out.
We know that is not the case, since islam himself said he had the choice between Gamrot, Poirier, and Volk, and he chose volk.