Not claiming in response to an argument --
...it all depends on how much of an argument is behind that wagon. If the topic is still being debated and you can be reasonably sure nobody's going to quicklynch, I don't think it's time to claim yet. But if a majority of the town calls for a claim, or the debate has largely been exhausted, or both, a claim is neccesary. Making policy of refusing to claim then, just because
you
don't think the case against you is convincing, is lynchably antitown.
Not claiming in response to a non-argument --
...
this
is the kind of nonclaiming that I believe is wagonable. For example, against an essentially-random bandwagon on day 1, you can argue reasons all you want but it's going to have to happen to somebody. Not claiming is unproductive. If the majority of the town wants it, you give it. Not claiming in response to a massclaim you disagree with is the same concept - disagreeing with the massclaim is one thing, but refusing to participate is another.
Almost any time a majority of the town asks for a claim, I think it should be given. Making policy of not giving it will generically hurt the town and help the scum.
...but, to the topic at hand: I say no to the first question, but yes to the second question.
If mafia towns make policy of lynching the player with the lowest protown skill:mafia skill ratio, something bad will happen. Eventually, if a handful fo players are considered the worst protown:scum players on the site, those players will be wagoned day 1 (and rightly so). Eventually, the games will be boring for those players, essentially giving them one of two options: Leave the site or purposefully reduce their skill as a scum player.
Just making policy of lynching players who make antitown policies - such as never claiming - is fine, though. If a handful of players stick out as extra lynchable based on their policies, their choices are to leave the site or just stop making that policy - not a hard choice.
My two cents.
Pie
I am a stand-up dude of genuine flyness.