@Ecky ah okay that's interesting, and actually kind of makes sense. AC uses quite a lot of power so I would expect the engine to open the throttle or IAC for that, but electrical loads are small enough they might just use a timing adjustment. The thinking is probably some combination of keeping the catalyst hot, smooth idle, and fast control, at the cost of a very small amount of fuel.
Timing retard is also used to intentionally limit torque by Porsche (if you look up one of their advertised hp/tq/rpm graphs, often there's a dead straight line for half the rev range, and the timing map shows decreasing advance), most likely to encourage buyers to spend more money on a higher end model
On DBW throttle cars, the throttle is also used to cut torque. Pretty weird stuff.