He hasn't said he's English, just that he wants to play for England, assume because he sees a better chance of success with England. If that's the case, then you can have him tbh.
He's only qualified for England via residency, and only then because of the recent change of laws where time spent in education are now allowed to be counted. Under the old laws he's have another 2 years until he was even eligible.
Given his sister is a Welsh international, I'm kinda hoping he's just toeing the line with his current comments in order not to upset the applecart at bath/England U20 but he'll do the right thing ans represent the country of his birth/upbringing when it actually comes to picking. Not holding my breath though!