Whoa, that's weird. I haven't seen any news about this at all, though, granted, I live in São Paulo, not Rio... but still.
I'm doing some googling right now and about their weird reaction to the drug: it was supposed to be diluted in water, but they snorted it instead. I cannot say that this information is correct cause I know NOTHING about drugs at all... but that's what I found while reading some recent articles.
His girlfriend has commented that, before Rye disappeared, it's known that he visited some slums. She also said that she doesn't see him as the type of person who does drugs and that, while he would go to the gym a lot, he was never much of a swimmer, so she doesn't believe he would've swum to the island.
Personally, there aren't many reasons for someone to visit slums. Other than some voluntary work or a somewhat morbid curiosity to see poverty real close, I can only think of drugs. And if he really was having a weird *advertiser censored* reaction to whatever he had (more than once, mixed with alcohol, according to the friend), I guess he could've swum all the way there out of desperation. Adrenaline and all.
We'll see what they say about the body that's been found...
I also do not know much about drugs let alone MDMA, so I'm just wondering if it's in the realm of possibility that if it was his first time using the drug - and has been reported that it was snorted and not diluted which you are apparently supposed to do (?) that he could of had a bad reaction to it and would that be likely? His friend also apparently had a bad reaction but clearly not to the extent of Rye since he seemed to be somewhat fine and with it whilst at the airport?
May I ask where you saw his girlfriend had commented on him visiting the slums? I know from traveling South America myself last year (and in fact any country a young traveler would go) that it's unlikely IMHO that you would seek out a slum to buy drugs when they are quite freely offered and sold between other young travelers, locals, clubs, parties, word of mouth etc?