I've seen two of these since 2.2 arrived. Once near a POI I was trying to find, as I approached it was obvious the ship was landed. In fact a change in LOD of the landscape caused it to be half buried for a moment before it popped up a bit higher. It definitely spawned as landed. The second time was right next to a mining installation with an AA turret. Looks like a new feature to make these sites a little harder to loot.
Viper MkIII, marked as system defence force in an uninhabited system. There was a POI nearby but I was in a hurry to leave and didn't stay to find it...
Approached a POI that I hadn't even noticed until I was over it, a mining station with AA turret. NPC Eagle, again tagged as system defence force spawned in landed position right next to it as I approached...