Your quotation of the law doesn't match what LII has in significant ways.
"Major Presidential and Vice Presidential candidates and, within 120 days of the general Presidential election, the spouses of such candidates"
It's troubling, then, that the Secret Service and LII have different versions of the law that establishes the authorities under which the Secret Service is to operate.
One if them is wrong in a way that directly impacts current events.
LII, from Cornell Law, is a pretty respected authority on the law, and it cites all of the legislation from which it draws its information, so I tend to think the administration is the one in the wrong here.
And if nothing else, the administration has incentive to mislead on this topic. Cornell only has downside should its reputation be harmed by being wrong.
@volkris@qoto.org I pulled my quote straight from the secret service .gov website.
https://www.secretservice.gov/about/faq/general