> Haven't open source projects done the rug pull too? Can't they relicense new code going forward?

They can, if the original license is permissive, or if there was a CLA. They can't for significant contributions under a copyleft license that was not done under a CLA. Something to consider when contributing to a project that uses a CLA or a permissive license.

> I get that there is an important distinction but from an adoption and evangelism standpoint it seems like an unnecessary crusade to push them away.

Depends on your goals. If source available misses the point anyway, adoption doesn't help, the message risks being blurred, and therefore you should push back.