It applies world wide.
No transponder I think they flew
vfr under FL18 and didn’t set off any alarms.
That's fine and dandy, but who in the vicinity would care?
Diego Garcia perhaps? Or maybe the Seychelles, fearing a planeload of tourists had got lost?
Sure implies someone who knew what they were doing, and possibly capable of landing the aircraft safely.
Back to "How far can they go" under those circumstances, and "What airfields were in range capable of handling the plane"? (official/unofficial/military because someone somewhere would have to be in on the heist, and that someone may be a governmental entity or highly placed within one)