Doomerism - I don't think that word means what you think it means (or you just don't understand what UBI could be the start of, don't know anything about MLK, probably all of the above).
Considering MLK's understanding and support of Marxist ideas, he'd probably be fighting for technological progress as long as it came along with UBI, since that's literally the basis of a better world for everyone, unlike systemic racism and capitalism he was fighting against, which really aren't comparable at all (sure, both could be used to fuck up the prospect and potential of technological progress and UBI, but that's the fault of systemic racism and capitalism, not technological progress and UBI).