I'd have thought the CAA would be within it's rights to make him take the UK air-law exam(s), but the rest seems a bit excessive.
Still, they're at-least consistent. When Colin Bodill (round the world microlight pilot) did his UK PPL(H) just after getting back, they made him do all the qualifying cross-countries. Now to me, anybody who has just flown solo around the world in an aeroplane with virtually no navaids, is not in need of their navigation skills assessing (assuming he'd meant to anyway).
G