If you have any clue how big an ocean is, then yes, it’s a rescue from absolute stupidity. And from starvation, sun burn, dehydration. But mostly from stupidity.
Yeah, I guess I didn't think apart how quickly the tides would pull him out from the coast. Maybe he's skilled enough at navigation to find his way back in open ocean? It's not impossible to swim across seas for experienced swimmers, and I think the bubble would help with exhaustion, though if anything it would make sun burn worse.
The problem with navigating this bubble is that even if your navigation skill is sublime, you still have to sleep. I'm certain that the tides and currents will displace you more than you can make back during the day. You're basically on a raft without a sail.