My understanding is if anyone is born on US soil, they are citizens. This includes embassies, military bases, US territories (Puerto Rico), etc.
I don’t think he is citizen, but this argument won’t stand, I’m afraid.
Your understanding is flawed.
Birth on military bases or in embassies does not qualify one to be a citizen.
Puerto Rico is not a US territory, it is a Commonwealth.
Not all citizens are Natural Born Citizens.
McCain was not born on the base, nor in the Canal Zone.