A sizeable segment of corporate-backed OSS is against Free Software for business reasons, and that mission currently aligns with the interests of the anti-rms mob. Those corporations see the FSF turning into a copy of the neutered OSI as a positive outcome.

Signatories of the support letter have all left links to their GitHub profiles or personal websites. Not comprehensive, but a quick glance of the 20 or so around my signature shows actual humans, most of whom are actively making commits to projects on GitHub in the past year or so.