Every nice welfare state has a lot of unemployed people.
France has a permanent unemployed class, with perpetually high unemployment as a result of their labor laws and generous welfare state. Those people are not starving to death.
Clearly UBI is in fact not necessary at all, so say the best countries in the world, from Denmark to Canada.
German unemployment benefits are conditional on showing evidence that you're seeking jobs. So it's still founded on the assumption that everyone able should be working.
So you are going to justify it like that?
These days liberals are falsely using the word liberal. A liberal is a person who supports the law no matter what. Not what your emotions say.
My interpretation is the opposite - a lot of events lately provoke critical arguments that use the objective verbiage of legality and human rights to frame emotional, subjective opinions. E.g. the line between a private platform reasonably removing a user or something a user posted for ToS violation, and an attack on free speech. Or the line between reasonably punishing an employee who has violated workplace behavior policies, and an attack on innocence until proven guilty. I would argue that, in this domain of examples, liberals explicitly favor reason and prudence, not extremity toward one side or the other (though there may certainly be cases where there is a general bias toward one side of the line or the other that arguably fails that ideology).