This is terrible advice.
If you register a .us domain, and if you do not actually have US nexus, then anyone can, at any time whatsoever, send a notification to the registrar, who will then ask you to prove nexus, you get like a month to write back. And if you do not, you lose the domain! It is delisted, as if you had let it expire, no grace period, no nothing.
It is extremely stupid to put work into something you can just lose any day randomly like that.