Well, something that bothers me much as player is that actuall reinforcment call.
It shouldnt be active while a port is conquested, i mean a port is blocked at this time, so how should this port send out any reinforcements?
Often you intercept incoming defenders, ending in a huge AI fleet spawing, making it able for the defenders to leave the battle and beiing invisible/invulnerable for the attacking forces and make it into the port battle himself.
I think, as long as a Portbattle is in Progress, this function should not be active for the defenders.