I assume that Bernie Sanders doesn't want to give those 50% shares in AI companies to non-US citizens, which is politically reasonable but intellectually wrong (a world where maybe 3 countries has near-infinite UBI and the rest not is extremely unfair in the normal left sense).
One of the interesting twists of wanting to put democratic control on powerful technologies is of course that everybody is a stakeholder and presumably should have a say - including people in other countries.