I am not sure if your original solution will actually work. For example an attacker can just spoof enough accounts to sample from your distribution to figure o

I am not sure if your original solution will actually work. For example an attacker can just spoof enough accounts to sample from your distribution to figure out the true center. Imagine spoofing a grid of users with let's say K fake accounts per dot, then if you plot the histogram of who managed to connect you will see a very clear bump in the 2d histogram in the shape of circle. The solution in your edit is much better.