that's food for thought there, john4200.

but the way i understood changes is that harry did think through all the possible options he had and becoming the winter knight was the best choice in terms of avoiding going "evil" eventually. i think he must have believed that being the winter knight would give him the most leeway to rebel in the future (since he had already seen lloyd slate do basically the same thing before when the guy sided with aurora). so he must have also thought that even if mab figured out he tried to cheat her by dying and she does something to keep him alive, then he still wouldn't be completely under her power or become completely corrupted.

contrast that if, for example, he had chosen to take up a coin instead. his chances of losing himself were greater if he had opted to go with the fallen. even though, yes, a human host can decide to give up the coin, being the host of a fallen angel seems to be really corrupting. even when it was just lash in his head, other people noticed little changes about him, like he was angrier than normal. and she was just a shadow.