Please, any player that can't perform an action as simple as running an overlap shouldn't play professional football. Also, we had Araujo trying to dribble to the touchline yesterday. No reason why he can't do an overlap while one of the CMs cover his position.
I’m sure that he can overlap, as you said, anyone can run forward past an attacker with the ball. It’s unlikely that he’d be good performing that role as center backs have completely different passing attributes to that of an outside back. So, while he probably would be fine overlapping, he likely wouldn’t be good with the ball in those areas.
Your idea of wanting someone to overlap Dembele doesn’t take into account how we were set up tactically. Xavi has us building up in a 3-4-3 shape so in this tactical setup, it would have been FDJ who would have been the player supporting Dembele.