Signal needs to release all the infra automation code behind their backend. How they setup and manage it all should not be secret. It also makes it easy to rebuild if for some reason they are compromised. They've ghosted multiple people about this question. There's no reason a 501(c)(3) shouldn't release it.
OpenAI is 501c3, should they also be required to release everything?
I’m not sure their tax status is the justification your argument needs.