What particularly strikes me is how he points out that this already exists in cultures. Even in villages in India, you'd find people simply willing to do stuff for each other. If you have a wedding in your family, the village will come together to cook and serve meals, offer hospitality to your guests and generally work to make everyone happy on the occasion. If you happen to be mentally ill, someone would still feed and clothe you, include you at least in some small way in their social life, and so on. You won't be abandoned.
UBI looks like a quantified version of this social capital. If we resist and think "why should someone else do nothing and get the benefits of my work?", the society has lost the practical generosities of village life and UBI might be a way to resurrect that. I personally find it pretty ridiculous that there are homeless and hungry people at all in the wealthiest of countries, and am certainly curious about what potentials UBI could unlock for them given they haven't yet fallen into antisocial ways despite their condition. Something is wrong if you see an old man in rags rummaging through a trash can for food scraps in a high GDP country.