These Affiliate organizations face a larger political challenge in signing a petition than individuals do.
Typically, they have an internal process that needs to both prioritize an issue like this (& many may only vaguely care about #OpenSource Initiative at all). Then, the org must go through an approval process internally to sign.
Since these orgs often have their own members, donors, fans, & otherwise must interact with the #FOSS public, you can help that process along by contacting them