[IG_Semmelweiss]

>>> but it's ok to strip it away if someone is subject to anti-trust action?

The 1st amendment is not absolute if there's competing laws against it. Which i believe is your point, or at least helps your argument as you will see below.

>>> unenforceable/illegal contract provisions are pretty common.

Agreed, for the same reason that it is illegal to sell your body parts. This is because the illegal provisions (freely entered between consenting adults) would be in direct conflict with another established law, and the constitutionality of said law would have been brought up in front of (higher) courts to debate whether X type of association does not run afoul of other rights.

>>> What is fundamentally different between banning non-compete agreements, and banning exclusivity clauses?

There's nothing fundamentally different except the former is now law, under the 13th amendment [1]. The latter has yet to do so. So you could be correct. The 13th amendment is a better pillar vs going strictly against the 1st amendment for (reasons).

[1] https://www.jurist.org/commentary/2023/02/rebecca-zietlow-13...