You're right that they do let him have the ball when we're actually attacking because he's the least likely to hurt them. But they also consistently use him as the trigger for their pressing game against us as we try to build out from the back in earlier phases of play.
It's not just about him cheaply giving away the ball under pressure (as he did with the pass to Matic highlighted in one of the OP's twitter threads, for example) but also because he struggles to gather the ball, turn on it and/or play progressive passes, instead being forced to immediately play the ball backwards to the RCB or sideways to the RCM. So even if they can't force AWB to give the ball away, or if they can't then target the RCB/RCM (knowing that's where the ball will going immediately after they press AWB) causing *them* to give the ball away, they're still stopping us from being able to build out down the right hand side of the pitch.