@Leigh414 The listing makes no mention of charity donations, so his status as an Airbnb host doesn't appear to be implicated here. I agree that it's inappropriate to pressure a guest for a donation, regardless of whether the cause is genuine. It would only be against the rules if there was some form of extortion involved, like the threat of a bad review or an illegitimate damage claim.
If your stay is complete, there shouldn't be any reason for further correspondence with the host - and he is not required to return your messages. If your checkout was less than 14 days ago, you can (and should) write a review that conveys your apprehensions. Other than that, I don't see a need for any further action on your part.