"big-boned" is a term euphemistically employed by many-especially the hefty in describing their girth (I just want to beee meeeeee...). Curtis writes with a hilarious note and even if one chooses to disagree with him his post is still very funny.
Anyway, genetics (big-boned) do appear to play something of a part in being on the heavy side, but my original impression included the mentally flabby, along with the physically overweight.
Chalk any preceived "anti" fat comments up to an ignorant novice who thought that somehow, someway the BDSM lifestyle was supposed to contain sexual elements. Personally, it is difficult to find the overweight sexually attractive.
Given the relative "size" of the munchers tended not to be the turn-on that was expected. Coupled with talk of "toys", etc., try as I might it did prove difficult to find much allure with what was assumed to be an entre into the world of BDSM.
But, if it mitigates any ill feelings of the hefty/toy minded, then just shrug at one clearly not as sophisticated as you, on the machinations of the BDSM lifestyle.