Just dropping it here that we do have 2-3 solutions to this already in case you didn't notice previous posts.
Not to take anything away from looking for a better solution, mostly for users coming upon the thread looking for a fix.
Among them my own little addon that's been linked further up this thread:
(it was waiting in the approval queue when I saw this post or I'd probably have used one of the existing solutions)
- Lose Control Options Fix (only tested with default Blizz actionbars, only suppresses the red-out when you have the relevant game option unchecked)
- Loss of Control Remover (unconditionally suppresses it, uses LibActionButton, tested with BT4, Dominos etc according to author)
- NoRed (from ArenaJunkies, the one Zork posted about at the OP, also unconditionally removes it)