Stallman is his own man and can boycott what he likes and explain why to others.
"Punitive" "teeth" as found in proprietary EULAs and various unreasonable copyright laws looks like jailtime and financial ruin.
And if you don't like a code of conduct, you can equally just stop participating in a community. Unlike rejecting a license, you can even reject a code of conduct and continue to use the software produced by that community.
https://www.softwarefreedom.org/resources/2008/compliance-gu...
That's the basis of eg Kernel enforcement, the most-distributed project out there by far.
In the particular case of Kernel development, contributors are NOT required to assign their copyrights to any shared institution, are perfectly within their rights to take any enforcement action against violators that they wish, and sometimes do exercise that right: https://www.zdnet.com/article/linux-beats-internal-legal-thr...