The idea that people aren't allowed 'second thoughts' is probably the worst thing to happen to general discourse.
Updating opinions based on evidence is good. Insulting and slandering people because they have different opinions is bad.
Edit: I've definitely seen people on Twitter and people in the media be overzealous when denying the lab-leak theory; but that's not the same as the scientists themselves doing it (which again, I don't know about either way).
Scientists confusing absence of evidence with evidence of absence (i.e. "we don't have evidence of lab leaks, so anyone claiming it's a lab leak is definitely wrong") -> joke of a scientist
Scientists making a statement not from scientific evidence but due to political expediency (see sibling post, i.e. "conspiracy theories are making China unhappy and they might not share data with us") -> political actors