I think it enhances the message of the BI experiment. The folks at YC have enough money to allow pursuit of their interests. Another poster quoted a study indicating there are 50 million people below the poverty line in America. If bills were not a concern, how could those people impact society by following their interests in entrepreneurship, science, literature, art, etc?
It just seemed silly language to me, especially in light of the program focusing on how money can alleviate the majority of poverty's struggles.