I agree, i neve rheard the argument of not working used against UBI. Actually i have heard that argument, but it is always int he form of those for the concept fabricating it as an argument of those against. I never legitimately heard it used as an argument against.
As for it being a safety net, in theory sure. But considering the harm it does as I already explained in thread, and considering there are non-harmful ways to accomplish the same safety net. Also considering it isnt really sufficient even as a safety net for most, I simply cant support the idea under this premise.