A good theory, more plausible than the bullshit Fox news put forward. Thailand is known for it's rampant prostitution and child sexual abuse, so this being a human trafficking smuggling cave (where the 'goods' are 'stored' until someone 'picks them up').
Bearing in mind this is the same Thailand that doesn't care if slaves in the prawn trade get physically pulled apart limb from limb by boats. So why they'd be concerned about this is another baffling mystery.
Flashlights can last a long time. Especially wind-up torches. Better question is: how did they get the photograph out?
Ignoring the obvious flob, the human body can't go without water for more than 3 days (I once managed 4, but lets just say I restricted my waste output). You lose physical energy after about 4 days of activity with no food. Apparently they've walked 4km without food or water (sweating demands even more water, and dehydration would be an issue).
Elon Musk sticks his nose into everything. He's trying to be like Bruce Wayne. Wouldn't be surprised if he paints one of his Telsa's black and goes out at night in an Elon Musk spacesuit.
Another question: if it's a cave, where's the electricity for the electrocution coming from?
Plenty of questions to ask.