Hi
As A bodhran player myself, I get really pissed off with people who give the rest of us a bad name.
I know when to play and when not and it's pretty obvious to me that this chap doesn't. Who MC's the club? perhaps talk to this person, maybe he could start the evening off by saying that it's lovely to have such a wealth of talent in the room, and that it looks like a good night of music and song yet again, however, would participants respect the wishes of singers who prefer to sing unaccompanied.
As a singer also, it is not a case of singing out of rhythm, it is a case of singing with feeling and altering the pace of the song to add expression, if he tries that retort again, suggest that the same is also true of a good bodhran player, which if he was, he would understand.
If all else fails, get a G penny whistle and just blow it, using any fingering, when he "plays" or sings
He may not get the message, but he may begin to understand how you feel!
Last resort - tell a bevvy of bodhran jokes whilst introducing your song, if he then joins in, point to him and say - see, I told you so!
Good Luck
Lucy