@dvallee40 , first it is confusing indeed ( at least for the uninitiated and the rest of us ) and so don't feel bad.
Section 7701 generally is a definition section while section 6013 is the defines actual eligibility, the election mechanism, the limits of such .
In your particular case , the letter requesting treatment of non-resident alien spouse as a resident i.e. the contents of such document is the only action required --- there are some items / information/ assurances etc. that are generally needed within the body of the request. Once you have requested ( and unless IRS has specifically rejected ) you proceed as if granted -- your return was processed, your refund issued etc. are general indication of granting. The quotation of the statute section ( correctly or in error ) does not generally affect the outcome ( unless of course you are arguing a determination ).
Once granted , the joint filing status remains valid unless voided by situations/actions called out in section 6013 -- separation/ death etc. etc.
Bottom line is don't worry about the request, assume it has been granted and is good for as long as you choose to file together.
Assuming that you used ( or requested ) ITON for the Non-Resident spouse while filing jointly in 2021, now that the spouse has SSN, use that for the 2022 filing. For tax year 2023, nothing changes vis-a-vis tax filing ( Married Filing Joint).
Does this help ? Is there more I can do for you ?
pk
