Of course, I don't think that has ever been in contention, except that one idiot on the forum that assumes that it is not possible. During Covid I bought a couple of those 500 minifig packs from Legoland and they were full of unique parts, some weren't even in the catalog. I think we can all assume that some parts on Bricklink were legally acquired and some were probably not. One thing I can say for sure is that now someone with a large quantity of illegitimately sourced Lego parts can still sell them, they just are forced to do it in lower quantity so they don't arouse suspicion.
IMO Bricklink should have said nothing and done a private investigation into the matter without shutting down at least 1 store we know of. I think reporting suspicious inventory is fine, I mean if I buy 1k joker figures you are damn sure I am running a serious business and will have all the receipts to back that up. The whole situation was just handled poorly in a knee jerk way that made Bricklink look like a bunch of children running a 100 million dollar company.