Just about all clans I've ever played the Battlefield series of games with have one rule in common: 'No attacking uncappable bases (UCB)".
On several of FS's Push mode maps certain CPs become uncappable once they've been taken by the assaulting team; the lower CPs on Bestine are good examples. I think a significant number of players are unaware of this fact, but those who are should think again. Straider's almost right. It's not that you can't attack those bases, but you shouldn't.
In terms of fair play, you are attacking a UCB with all the potential for spawncamping and base-raping that comes with it. Tactically, it only takes one squad leader to sneak past you and (on Bestine at least) you are too far away to defend the first two top flags. I have done this, and it's bad news for the Imperials!


Mmm... vanilla!