The problem with the 1st Amendment is that it protects all speech (in general, and if you quote yelling "fire" in a crowded theater you have not read the case law) no matter how stupid that speech is. The issue is that anything else could be a slippery slope to authoritarianism. Drawing that line is hard. Education is the key here however some people seems to be to stupid to be educated.
...they think THEIR bodily autonomy has no limits -- not even where sane people would see that it has to be limited to not encroach on OTHER PEOPLE'S bodily autonomy.
I'm not so sure about that. Stands to reason, AFAICS, that "MY freedoms (and screw yours)!" ideologically resonates more on the right than the left: The whole left-right dichotomy is one of ~ "my freedoms above all" vs "freedoms for all, balanced with responsibility for all".
I think that this is extremely simplistic. For example it does not account for individualist anarchism or the collectivist "for our country/nation/race" pushed by various fascist governments.
I can't see how "doesn't cover absolutely all corner cases" equals "extremely simplistic". I'm fairly sure that in broad terms, "left / right" covers the political spectrum the absolute majority of people inhabit. Your objection feels like futile quibbling to me.
I think that you are stretching it a bit here. Claiming that individualism is responsible for that seems unsubstantiated.