Earlier quoted context omitted.
> nothing is technically stopping you from walking into a SCIF with a phone most of the time That is ridiculous. I've been to multiple embassies as a nobody and no electronics were allowed and this was strictly enforced.
I agree it's ridiculous (though not in the way you meant), but he is telling the truth. I don't doubt that there are facilities which are watched as closely as you describe, but not all are. I have worked in a SCIF where the only thing stopping me from bringing in a phone was the fact that I said I wouldn't, and I keep my word.
They usually make a big deal out of it.
This in embassies between friendly nations!