If the US person's NRA spouse has no US tax filing requirement, there is nothing that stops that US person from claiming standard deduction.

If the NRA spouse has a US tax filing obligation, it most likely means that there's more than just FDAP subject to final withholdings and that there is probably US-ECI for which I/D may be claimed, however small that amount may be.

§63(c)(6)(A) clearly stipulates MFS spouses would not be eligible for S/D if either itemizes.  Subparagraph (B) then states that NRA's are not eligible for S/D.  If the Congress had intended anything different and that special considerations should be given to US persons with NRA spouses who are required to itemize, one would surmise that such a treatment would be codified.

At the end of the day, it is long established that federal income tax deductions are a matter of legislative grace.  If a taxpayer believes a deduction is allowable under the Code, the burden of proof is on the taxpayer.