well, I don't think China's long range SAMs are stationed in the area, so it makes sense they didn't get picked up by SAMs. As for PLAAF, the nearest regiment looks like a J-7 regiment, so I'm not sure about its readiness. There is the first J-10 regiment a little further away, but it would take a while for them to meet the Burmese plane. It doesn't take that long for a fighter jet to travel 100 km.