The worst problem that a team can have is non-visible work. Work that is being done by team members that isn’t on the Scrum Board. This rogue work sucks the capacity out of the team. These hidden distractions will reduce focus and velocity and this invisible work has no validation and learning component to it. It is a rogue wandering to do list of some sort or other. And, the team, and the rest of the company for that matter, have no visibility on the work which means that someone, somewhere, is going to be in for a surprise, of some sort. NO SURPRISES. Either kick the person who is serving other requirements off the team so that they can join whatever team has this mandate, or, make them a chicken so that they can observe but not distract, or, bring them back on as a pig and get visibility and meaning to that rogue work.