As stated in the article, 50% was chosen only because it's the rate where calculations are simplest, it's not the proposal (it'd generate way more than the current government tax receipts). Income tax rates under a revenue-neutral negative income tax could remain pretty similar for those about the threshold; it's really just replacing non-cash welfare-cliffed benefits with a smoothed cash transfer.

I reread your article, and maybe I was being too harsh. You gave an example of a 50% flat tax (which you admitted is too high), but I think what would be more interesting is to see what a progressive tax would look like to remain revenue neutral while providing a reasonable level of BI.

I dont think basic income is tenable in the US without raising taxes on high income earners, perhaps significantly.

Yes I'd like to do that. Net tax burden (taxes - BI) still shouldn't change under the revenue-neutral approach, since they'd be equal between NIT and BI.