Magic is by definition outside of nature.

A magician would disagree with you :D

If this were a highly advanced alien with probability manipulating technology, that would be a different question.

"Any sufficiently advanced technology is indistinguishable from magic."

If presented by observable evidence the supernatural exists in one specific case (the genie) then it is reasonable to suppose there may be other supernatural beings.

Imagine I was a person who had never seen a narwhal, and thus didn't believe they were real; suppose I believed them to be supernatural creatures. So to prove me wrong, you bring me to an aquarium and show me a narwhal and say, "look, a live narwhal. See? They are naturally occurring creatures". I could respond with, "well no, that's obviously a supernatural creature, and now it's reasonable for me to also suppose that unicorns exist!" Do you see any flaws in my logic?

We've hypothesized of a situation where we have an observable creature in front of us. At that point, regardless of how "magical" we believe it to be, it is, by the definition of "supernatural", not supernatural. However, when it comes to supernatural beings that we have not observed, this genie has not given us any more evidence for their existence.

Happy halloween!