I never truly took exception of him not doing it.
But it kind of sounded fake once he did come back and fought Bisping. though. All his talk about being small went up in smoke.
And when he refused Whittaker, kind of sealed it IMHO.
He should have never been expected to do it in the heart of his WW GOAT run just as Anderson was never going to do it in the heart of his MW GOAT run. In that regard Anderson was always more honest with himself saying "it is not a fight that interests me... I am happy in my category" when asked about a fight with GSP.
But fighting Bisping did not show anything to be fake. That actually aligned exactly as GSP always said his MW attempt would occur. 'Once he was done with WW and could take the proper time to gain the weight'. You can call Bisping convenient and opportunistic but that is not GSP's fault. He had already announced his intention to return prior to Bisping taking that belt and had, had several negotiations with the UFC about a new contract, and with Bisping taking that belt the stars aligned. No way GSP should have focused on any fight but that one. Any fighter, including Anderson would not do the same.
And GSP's challenges in making MW and holding the weight were real. He went in far lighter than planned against Bisping, so I do think his MW career was going to end with that fight regardless of who was next. BUt I also feel GSP even if healthy was not going to continue at MW. He is just too small and knows he could make LW and the allure of 3 belts was, imo, always in his sights. His team dropped too many hints of him 'being able to make LW easier than MW' for us to not connect those dots. And again that is not something I blame him for.
When Anderson went into legacy mode he and his team marched in to the UFC offices, said he maybe had 8 fights left and 'he only wanted the biggest fights at LHW and MW'. That is what happens when a long term champ and GOAT sees his retirement coming. He wants to pad up his GOAT resume with some 'name' wins. They don't care about contender runs, defending belts or the other day to day stuff normal fighters have to deal with and will gladly be opportunistic.
GSP has just managed his career, and got lucky in terms of his legacy matchups and if he gets super lucky one more time somehow Conor will beat Khabib for the LW title and you can bet Conor would get GSP next. But regardless just winning the LW belt would be huge legacy wise even if from Khabib or other.