Thanks @alexu for the really thorough analysis! 
This confirms @tmshlvck’s findings. Automating and extending these checks to other nodes sounds like a great idea (particularly in light of the new proposed reward boosts based on country). I’ve since updated my SM review tooling to make use of a more accurate geolocation service (thanks @LaCosta for pointing me to it).
Out of interest, could you imagine the IC being able to utilise node machines themselves as probes at some point in the future? Not that that’s necessary, but would be cool to take advantage of the geographically distributed network that the IC already has at its disposal for this purpose. Just thinking out loud.
The other issue is related to KYC and independence (e.g. NP aliases).
@Zane and I had a zoom chat this morning before work to catch up and to discuss this, which I found really useful. When I’ve got some more time I’ll write up one of the ideas that came out of our chat.
I’d also like to further clarify some concerns.