I know, I was shocked when I looked at the Harrisburg roster.
I think ideally you might move him to Potomac, but the boy obviously likes challenging himself, and it's highly unlikely he's going to completely fall off the table in AA. Even .260/.330/.500 would be a tremendous success for an 18-year old in AA, and I think I'd bet the over on that.
Remember, he hit .343 in the AFL with a 1.000 OPS. He hit .389 with a 1.000 OPS in spring training. Those are obviously limited sample sizes, but given those performances against competition at the AA level or above, and with him absolutely destroying the Sally league, there's no reason to think he'll be overmatched at AA.