I'm not an advocate for BI but I think I've given you an accurate summary of what BI proponents would say about a NIT. E.g. listen to this Econtalk episode[1] where the host / guest have a debate on this exact topic.
Your argument that BI would be revenue neutral for some taxpayers and therefore we should just use NIT to avoid the sillyness of the government taking $1 from you just to give $1 right back to you isn't wrong, but it's missing what BI proponents are trying to achieve.
It's mainly about achieving roughly the same ends with different optics, and the comparison to Social Security is often brought up. Enacting any system like this is going to be politically difficult, and BI proponents believe that "everyone gets the same" is an easier sell than "this is another subsidy for the poor".
1. http://www.econtalk.org/archives/2017/01/michael_munger_3.ht...