I'm not sure why people are getting so hot under the collar about QRA. It would be unusual for a track of interest requiring a Q launch to originate from just south-west of London, its ID will have been known from the time it left Fairoaks, and it will have been in the system because it was squawking (hence the FR24 trace). Of more interest, at least to the CAA, will be why this individual set off for Valley without establishing that it was open, and without the PPR tick. Come to think of it, as he was operating an N-reg aircraft he presumably has an FAA licence, so they may be interested too.
Correct call from A/OC Ops not to block the departure, which would only have led to more trouble, and the landing fees will no doubt be collected at some stage.
As for why this man decided to land at Valley, perhaps he didn't see the "This is a prohibited place..." signs from the air. Having allegedly had the virus, perhaps he just flew there to test his vision? That would explain everything, and would make it a very reasonable and legal action too.