Bullshit, two wrongs don't make a right. If someone responds to team attacking with team attacking, then both players should be disciplined. If there's a hacker in the server, can I show him up by getting my own, shinier hacks? Of course not.
The admin should be able to keep control of a server and not take sides in an issue. No matter how much of a cunt carmichal is the admin should be able to deal with a situation properly without everything descending into chaos.
With that said I don't think this is abuse, rather just really shitty admin-ship.