Imo, "fighting" (more like running around) after the flags have been successfully capped is basically exploiting a glitch just like walking through walls and shit, which is a bannable offence. Is it the admins' fault that people can exploit parts of maps? No, but they should make up for it by making sure people don't do it. Same goes for the flags not working sometimes. If the last people alive on the losing team are 100% giving it their all to fight and make sure that the round ends asap, then sure, that's the best we can hope for and they don't deserve a ban. But camping a roof til you run out of ammo or "looking for a melee weapon" isn't nearly the same.
But that's just my $0.02 and I barely even play anymore, so RIP.