Uriah

It doesn't address any of the issues mentioned in that thread you linked, just mentions one about genetic distance and then ignores it.

A splainer’d be great

Loads of things that could go wrong when testing a polygenic score using one population as the discovery & training sample on another population. Effect sizes, effect directions, interactions of SNPs can vary across populations;

Ashkenazi Jews are mostly European by ancestry, not that distant genetically.

What do you mean by mostly European? They are almost full EEF, have 0% ANE. In this case Turks and Iranians would be mostly European too.

Mostly Italian, plus some French and Eastern European.

This seems unlikely to me, their position on the pca would be different.