I think it is clear that Ben has the ability to make the changes but if he was just to do so it would appear that he was not handing over responsibility adequately. This also assumes that he has the time and inclination to do so.
There is a reason why Ben does not have role and further to this a reason he has not requested to do it. As a relinquishing of the responsibility of the role must lead to the expectation that he "fixes stuff" should also be relinquished. I am almost positive if requested to do so by Rob he would assist but this would be for him to decide and for Rob to request.
The tit-for-tat stuff though is awfully dull and the phrase "I told you so" probably was not the most constructive!