Why aren’t you just spending the $206 to make their vacation better, instead of going through some dodgy eBay third party selling elite status?
Frankly the odds they’re going to get comped upgrades in a place where everyone and their uncle is coming for tourism resemble lottery odds (read: tons of Marriott elites all competing for upgrades because they’re all vacationing here after grinding through a bunch of blah Residence Inns and Courtyards) And $206 should buy you more than just breakfast for a few days.
And that’s completely aside from Marriott possibly deciding that your friends might be in on a scam and cancelling accounts, etc. Just no. Don’t do this. Hawaii is a market where cash is more meaningful than DYWKIA and waving around a loyalty card. Spend the cash directly on the vacation.