Headphones?
I mean, it doesn't bother me - I'm the guy with a Model M (or rather, was; trying MX Clears now). I used to sit near three other Model M users.
I guess it's like any other office noise (loud conversations, loud servers, radios, etc.). Talk directly to the culprit and maybe mention to your boss if it's an issue. Try to establish a relationship with the individual other than being the keyboard nag and maybe it will get somewhere. Don't act like you know everything, or necessarily more about keyboards than the keyboard owner. Maybe just DGAF.
Or maybe use it as an excuse to buy more keyboards yourself to let the culprit sample. :-P