I'm conflict-averse, buuuuut I'd probably bring in treats for my own birthday and openly tell people to go get some of the birthday cake I brought for myself!
Celebrating your own birthday, AND bringing slavery and cannibalism to the office??
Snark aside, I like this idea. This is one of of the things that in the grand scheme of the business is not a big deal, but at the same time, it is. Could maybe all the peons from the same birthday month be celebrated? We did this at my previous company, which was so cliquish it reeked of a high school hallway. This way, those who wanted to be big and important could be, and those of us who wanted to grab treats and hide at our desks could.
I agree with the sentiment from another post--if this was a cost-saving measure, why couldn't anyone just say so, and stay consistent? My guess is that someone ruined it for everyone somehow (which also happened at my old company in other respects) and that there is some disagreement, so certain parties get a pass, but not all.
Office aside, if possible, I recommend celebrating birthdays at a bar (if appropriate for the group) or restaurant after work. There, it's an even playing field.