If I understand correctly, the problem is that while you can construct an Stdio.Port or an SSL.Port from a file descriptor, you can't do so with a Protocols.HTTP.Server.SSLPort, because the create function of this class (taking 1-6 arguments) unconditionally calls Port::socket::bind().
In which case I guess the solution would be to add a variant create() taking either zero arguments or an SSL.Context (to mimick the one of SSL.Port) while leaving the current one as it is for compatibility?