Food should be with held unless their families provide it.
I've spent a lot of time in Thailand, to include living there for about 2 1/2yrs. IIRC, it is the responsibility of the family to provide food for them.
I'm also surprised that the locals, even though they are some of the nicest people on earth, didn't administer some justice before they were arrested. They do not take kindly to slights on their King, their religion, or their historic sites.
My best guess, is that those two idiots will spend a couple months in a Thai prison before being sent home with "never to return" stamps in their passports.
Not an uncommon condition of imprisonment in third world countries.
It gives families a strong incentive to raise there kids to not be criminals.
Imaging how different urban youth would be if mama's welfare payments were docked the amount it costs to feed them in juvie...