When I lived with a roommate we both had dogs and our own rules. One of the rules was keeping treats separated (my dog got her treats, her dog got her treats, etc), so long lasting treats were locked in Jazzy's crate for her and she was able to access them when she was in the crate while the other dog never touched them.
You can train both dogs, but realistically it doesn't sound like your roommate is going to go for that so just let your dog have his treat and take it away and store it when he's finished. Don't leave them lying around anymore
Jasmine - Female Miniature Poodle - born Aug 15, 2010
Loker Delgado Von Stalworth - Male GSD - born Jan 26, 2012
Koda & Zazu - 6 year old male cats
Alex - Male Cocker Spaniel (rescue) - RIP Cuddlebug 2007-2010