I understand what you're saying, but that's not his fault.
Whittaker has been ready to go since February and is alright fighting anybody the UFC offers him, the thing is the UFC haven't given him anything and at one point told him to wait to see what happens with Izzy/Pereira 2.
Whittaker is a guy who's proven that he'll fight anybody the promotion puts in front of him and he hasn't been rejecting any fights, he just hasn't been offered any.
I'm fine with him having to get another win or two before being considered next in line for a crack at the title, but if the UFC booked him a fight during those three months since the Costa bout was cancelled like he's been asking them to then his case for the next title shot might be a bit better. The truth is the UFC screwed him over here.