Having the UBI conversation in the context of the US is frivolous. The US has no populist or labor presence. We'd need 5-10 years of building that presence before we could even begin to talk UBI, and even then there'd be a lot of obstruction.
(1) You are strategically wrong, in that having policy goals (e.g., UBI) and talking about them front and center has always been instrumental in building labor/populist movements.
(2) You are factually wrong about the current context, in that the US has substantially and political relevant populist factions (both the energization of the one on the right and the alienation of the one on the left were key factors in the 2016 election.)