Mobile sites take _a_lot_ more effort - to get something working at, say, desktop + tablet + tablet portrait + small tablet + mobile landscape + mobile portrait takes (unsurprisingly) 6 times the design effort and often the same front-end development effort. Unless a project is aimed at the mobile market, most don't care enough to multiply their budget six times.
Saying that a desktop site works fine on modern smartphone / retina displays is a fatuous comment - your fatuous fingers aren't going to scale to retina resolution when you poke that link. To make a site work well at that size it needs designing for that size.
SG is the real deal - he's been around forever, he's been an outsider forever (i.e. since the internet was conceived, and information was free), he knows the limitations of the "security" measures out there and he can call BS on anything in my book - his proposal stands up to scrutiny, despite whoever he's pissed off in the past. Onward the SQRL!