The headspace of "anyone is better than Putin" also means that people that are worse are praised. Someone that openly calls Muslims "cockroaches" and extreme nationalism isn't exactly "better" than Putin's similar stances on the LGBTQIA+ communities. So it is very possible for Navalny to be worse if given the powers Putin currently has. The real point is that it isn't a good thing to blindly praise/support everyone that openly attacks Putin as some "hero of freedom" or something like that.