You just advised illegal acts by saying to steal it and say it died. That's theft. Sorry.
I would have the caretakers tell the kid that they will find the snake a new home UNLESS the kid ponies up $XXXX.xx for "boarding and care" they have been providing. Figure up a medium level amount that he would pay per day, figure out about how many days, it should add up to a ton of money. Tell him that otherwise they will sell it to pay the "boarding fee".
He will probably say "Sell it I don't care!!" and at that point the caretakers can hand over the snake for rehoming. If the caretakers don't want the snake, they should be telling the kid what's going on or not. At this point, THEY are the ones who have custody and THEY would be the ones getting charged with animal neglect(which goes on their records!!) so they should be agreeable to whatever.
Not ALL animal controls or humane society groups hate snakes and kill them. Many do however, so it would depend on what area you're in. If the local animal control "euthanizes" after 24 hours, at least the snake wouldn't be suffering any longer, but the best would be to convince the kid to give up the animal.