They have provided reproducible builds for almost a decade https://signal.org/blog/reproducible-android/ https://github.com/signalapp/Signal-Android/blob/main/reproducible-builds/README.md
Signal Servers are using AWS and are spread throught the world. The entire protocl is build to remove any need for trust in those servers, so they migth as well be places in the datacenter of the NSA. So in the end it will be the same result. With decentralized protocls like Matrix you may get lucky and not have your small server taken down because it only hosts a few users, but if we are using the number of users as a metric, Signal would fare better against server takedowns, since all users are replicated throght the world, while my matrix server is the only place where my user data is stored. Then again both can deal fairly well against takedown ins single countries.
You can just as easily identify servers of a decentralized platform and block them. The disadvantage of a central service would come into play if say the US were to intervene, though Signal has already said they would move abroad if that was the case. For network level blockage it makes no difference if the service is central or not
Why are you so keen on spreading misinformation around? A feature you dont like does not affect the trust in the restof the application at all. Also, the integration of MobileCoin is part of the wiki page as well.