The connection here is that sybil-proofing is a (the?) major bottleneck to cryptoeconomic UBI schemes.

That’s like saying SSN (or other gov issued ID) solves poverty.

Some people believe that government issued ID in conjunction with a government that implemented a UBI scheme would indeed improve poverty. Andrew Yang wrote a reasonable book about the idea.

sybil-proofing in blockchain systems opens the possibility for any person or community to take a shot at implementing UBI. Could someone succeed in creating a token that retains some level of value long term and also consistently tops up at some rate in everyone's wallet? Beats me. But sybil-proofing is absolutely blocking issue on that front.

Are you serious?

I am serious that it is straightforward to create a token where everyone on earth gets X/day in a sybil proof system.

Making this token retain some sort of value is of course an entirely different problem, and I don't have strong opinions on whether someone might pull it off.

Yes.