I think you're trying to have it both ways here... unless you mean something by "cold blooded" that is substantially different than how I would use that phrase.
To me, cold blooded has a distinct negative connotation. It implies the party that was cold blooded did something wrong.
So you're saying in the same breath that the C's were both right and wrong... which is mush.
It's not mush though.
The Celtics were both right and wrong.
From an emotional/loyalty point of view, what they did was wrong. The guy broke himself trying to carry that team as far as he could. You said yourself that, as a fan, you had mixed feelings about it.
But, from a basketball perspective, it was absolutely the right move. The Celtics are trying to build a championship team and moving IT brought them closer to that goal.
I'm sure Ainge had mixed feelings about it too. He knows what IT did for the team and what the optics were going to look like (even among Celtics fans). But he had to do what was best for the long term, regardless of how bad it looked in the short term.