Yes, she was, but I think the question you're trying to ask is, if she was alive, did she deserve to be punished?

I don't think so. Some of my friends do, but here is my reasoning. Silena only became a traitor so in the end, she could save her friends. She told the Titans that there was a creature only Ares children would fight, ands they were not fighting in the war. That's why she went to convince them in the end, so t=she could throw the Titans off.

No.

Luke manipulated her and lied to her.

He's the real traitor.

She WAS a traitor, but by bringing Ares cabin and fighting the drakon, she redeemed herself.

She was a traitor, because she did betray them but she died a hero.

Well yeah she WAS a traitor no matter manipulated or anything. But if your question is about her deserving death then no she didn't deserve it.

Speaking on technical terms, Silena was a traitor. She was manipulated though

Luke is the real traitor. Silena is a traitor. I’m sorry but she wasn’t a kid anymore and she should have avoid talking to Luke, in the first place. He also tried to get Annabeth on his side but Annabeth didn’t help him. Just be realistic Silena shouldn’t have talk to him. She was a hero, yes. But she wasn’t that innocent at all. She had enough courage to die in order to save her friends but she never talk to Cheiron about Luke?! Silena should have told Cheiron about those stuff when she was with Beckendorf.