I mean sure, but that doesn't really change the underlying facts.

They were operating on false information, but the fact that operating without a taillight is legal was confirmed so why would any evidence found during a follow up search not be fruit of a poisonous tree?

It shouldn't matter what the officer thinks, it should matter what the law is. If you prove that the probable cause is bunk, then the search wasn't legal despite being done with "best intentions".