For me the companion reactions are fine as is and I wouldn't even mind if they were only there if the player doesn't decide to go after him if given the choice. I feel like any further changes to their reactions are unnecessary.
The issue has always been that the player isn't allowed to go after him. Even if there is no solution to shield him offered in the moment, it can be implied that you'll find one before the scene ends and it then either goes to Karlach's scene or cuts to the ending scene if she's not in the party.
