I don't understand what the argument is about. The player deliberately left Vedomina with expert necromancy, knowing that it's forbidden. If they didn't want to fire her, they could have asked the opponent if they were okay with it. Otherwise, the rules have been broken, and what she was doing isn't really important. You could just as easily say, "Well, I opened the cartographer, what's the big deal, he didn't have much of a chance anyway..."
Okay, I don't see the point in arguing further. If someone thinks that rules are just there to be followed and to nitpick them after losing, that's their business. I stand by my opinion and am fully confident in my rightness.
A player demanding a technical victory on such grounds doesn't deserve any respect, nor do the judges or the arbitration committee if they award such a technical victory in the event of a complaint from such a player. I myself have used freed forbidden heroes (Isru, Vidomina, Mullich) as scouts, without engaging them in any battles, and I haven't received any complaints from opponents about this. If I did, I would tell them to go away, and maybe even very far away :D