I don't think anyone has a problem with you taking that rope. In fact, most if not all people glad that you did.
I think just about anyone who ice climb has a problem with you being on that route given the condition it was in. But since I wasn't there, I don't know the detail of what makes you decided to climb that route when it's clearly falling down.
So if you want to talk about mistakes. The mistake isn't that you took the rope, it's that you were climbing the falling ice route in the first place.
BTW, what did you say to your belayer after the climb?