a) I'm not sure it logically follows that the hikikomori would be a particularly artistic group, thus don't understand the assertion; b) how do we know they aren't? By definition, they wouldn't be out promoting their works or gaining recognition.

Also, there is at least one example of UBI contributing to an increase in activity:

"According to the research, 31% of BIA recipients reported an increased ability to sustain themselves through arts work alone, and the number of people who reported low pay as a career barrier went down from one third to 17%. These changes were identified after the first six months of the scheme and remained stable as the scheme continued." [1]

[1] https://musiciansunion.org.uk/news/ireland-s-basic-income-fo...