[Maya had talked to Franziska over Manfred once - and though she couldn't crack the other girl, they had made plans. To watch him. To stop him if necessary. That combined with Maya looking over his conversation with Edgeworth (what of it was public), leads Maya to snap back (rather childishly, all things considered):]

Oh, really? Because last time I checked, she wasn't talking to you, but the whole time I've been here we've been friends.

[It's not even being called worthless that incenses her (because deep down, she knows it's true), it's, as always, his attitude]

I'm telling you the truth. You can either accept it or continue throwing a tantrum on the network, it doesn't make any difference to me! But don't think for a second you're the only one that cares about her!