I get your point, but not really the same as leaving one of your drunk friends to go swimming on their own which is apparently what happened. Uness you think there's nothing wrong with that either?
There's no point in speculating when you don't know the facts.
FWIW, I know John's circle of friends quite well and I've seen/heard no mention of this at all. He lives in Purton and from Taw Hill, Mouldon Park is a cut through to the village. It might be true, but equally it could just be people putting 2 and 2 together and coming up with 5, just because of the words "pub", "drinking" and "lake" were mentioned in the missing person reports.
Whatever happened, it's a tragic accident and another young life lost.