So, if I keep my cold storage coins in a legacy address, how does the affect anyone but me?

Attacking segwit isn't going to accomplish much at this point anyway. That battle was already fought, and the pro-segwit side achieved a major victory. I agree that any negatives about segwit will remain big blocker talking points, as they try to make BTC look weak. That doesn't mean there aren't still legitimate criticisms of segwit, and lightning, for that matter.