Short answer:
No
Explanation:
It was ruled in CoE Digest #119 that a player may use resources that affect attacks/strikes during his opponent’s turn if he is facing an attack from Hounds of Sauron or Traitor. However, the rules for taking actions during combat actually don’t override the restriction that resources can’t be played during an opponent’s turn; there are a few exceptions that do allow resources to be played during an opponent’s turn, but Traitor isn’t explicitly one of them.
Also, note this entry in the CRF, Card Errata and Rulings:
However, as Konrad Klar pointed out, according to the rules characters don't actually choose to tap for full prowess. Hence, we will reword the CRF entry for Traitor in the next CRF iteration:Traitor.
Characters facing a Traitor when it is not their turn may not play resources, but may still tap for full prowess.
This ruling overturns CoE Digest #119 Q5 (and note that we’re doing a separate entry for Hounds of Sauron).Characters facing a Traitor when it is not their turn may not play resources nor take other actions normally allowed during combat (i.e. the defending player can’t play resources to cancel or modify the attack, can’t tap to support against a strike, can’t choose to remain untapped against a strike, etc.).