Technically they aren't.
Due to logistical arrangements, the Iranian team is hosted by Mexico. They are staying at a training base in Tijuana, and are commuting into the United States via charter flights for their fixtures.
I guest this is a bill clinton Thule deal of host.
Mexico is their host.
But if I stay at a friends place (they host me) but if I go to a party across town, they host me as well, as I’m welcome to come to the party.
I don’t lookup the definition of host. But think it applies in both cases.
They are chartered on U.S. soil to only play, and then return to their training base in Mexico after each match.
but if I go to a party across town
The party is hosted by FIFA, not the government.
The government doesn't decide who FIFA can host into their own competition.
The government granted access (and exploitation) to facilities and stadiums for the entire duration of the event.
Well said.