“I won't die,” Wolfgang says dismissively, though they obviously have no possible way of knowing this. “Why can't you take a person? You take your clothes, why not other things?” They look around the shop, but there's not much here that isn't really tiny and thus wouldn't offer much conclusive evidence if he were to try to take it with him and it survived. Size would be Wolfgang's chief concern; telekinetics, for instance, typically have a weight limit.
They get up and go into the back, returning a second later with a beat-up old acoustic guitar. “Here, try to take this first. If it doesn't explode or nothing, probably you can take like, a person.” Okay, so it's not quite person-sized, but it's the closest they have, and would offer a pretty compelling argument in favour of Michael being able to take large objects that aren't a part of him with him.