It is indeed Elite that launches the Oculus store, and not PiTool, and this has been going on for ages, with other headsets too.
The game supports both the Oculus runtime, and OpenVR (SteamVR), and pokes them at startup, to inquire whether there is anybody home – presumably Oculus first, before moving on to OpenVR if there was no Oculus headset connected (I had a Rift and a Vive connected at the same time, at some point in the past, and ED would launch on the Rift, then (…and I could play another game simultaneously on the Vive, on the same machine :9)).
The behaviour came with one past Oculus software update - I do not know whether it is because Oculus got more attention-craving back then, and launches the store despite a negative handshake response, for that reason, or because ED does not hang up the phone properly.
You can stop “OVRService”, to prevent it, but may want to restart it, should you want to play something off the Oculus store. :7
( EDIT: Frontier really need to interest themselves more with VR, by the way; The openvr_api.dll they distribute with the game is from 2016. I tried a while ago to replace it with the most recent one, on the extreeeeemely slim desperate hope it would make the game magically behave itself with canted cameras, but I had of course no such luck. :7 )