Better wait for him to explain on why he opposes Signatureless Challenge. Maybe he has a point opposing such which you haven't got your eyes on. I would say PM him making aware of this thread.
3.I don't think you quite make a valid case for someone to be thrown out as a merit source.I mean maybe they have a slightly different opinions about your stuff but that doesn't mean they are incapable of judging one's post quality.I could be wrong though.
Totally agree. Eitherway even if he is removed from merit source , that doesn't means that he might have a different view towards your campaign.