Without being in the room I really have no clue. I'll leave it to the Pegulas, who know what happened, to make the decision.
If they feel he had a large hand in hiring Rex and they want to part ways with Rex after just 2 years I'd have to assume that they'd likely part ways with Whaley too.
On the other hand if he had other candidates that he pitched to them and they went in their own direction anyway I can't lay that at Whaley's feet.
Posters love to make wide, sweeping, assumptions and criticize Bills' management for those assumptions. Bottom line is we have no idea, even if we want to convince ourselves we do.