Why? For those of us in a state with income tax, wouldn't a better place be in taxable so we get the state tax break?
I was saying that T-Bills
could be held in in an IRA, if one didn't have cash in a taxable account. I believe @aja8888 was referring to the benefit of tax deferring the ordinary income generated by T-Bills.
My opinion is if you must generate ordinary income in a taxable account, then T-Bills are better (than CDs or MMFs) due to the state tax benefit. However deferral is better still, although most states don't give you the benefit upon withdrawal from the tIRA.