If the news cycle contains people saying "lets not rush to judgement about these people marching with literal Nazis" then I'm willing to wait like a week before sharpening the pitchforks for Wheadon. I don't think having a wait-and-see approach here is unreasonable.

Speculating about who an accused adulterer may have committed the act of adultey with doesn't seem like a huge stretch to me. Since his wax-wife was hush hush about this for years until now, it's unlikely that it will evolve beyond the he-said she-said stage unless Whedon's former cheating partners step forward themselves.

So no, wondering if Whedon essentially made a cuckold of someone else at this point isn't beyond the pale of reason at this point. Rather given how Whedon's website got unceremoniously taken down and he isn't defending himself aside from blaming the patriarchy for making all those other women accessible to him, I think extending him the benefit of the doubt is the unreasonable approach.