The whole website and list is dedicated for self hosting solutions. Unless it's peer to peer, any client apps aren't really the self host-able part, so it only makes sense to include the server side of the software.
I don't know about other people, but the only thing I don't like about Signal is that it is centralized. It seems to be the only option to actually get everything right for security though from what I hear.
Who will enforce the ruling assuming it does happen?