The main issue seems to be that they are not only blocking people actually in embargoed countries, and furthermore not only nationals of that country, but every

The main issue seems to be that they are not only blocking people actually in embargoed countries, and furthermore not only nationals of that country, but everyone who has ever used the service from an IP geolocated - or otherwise - associated with embargoed countries. If former nationals are more likely to have visited an embargoed country, it could conceivably fall under discrimination laws. But it is probably even more problematic if using a service from an country specific IP actually should triggers the embargo from a legal point of view? Then we have a problem, because suddenly you won't be able to use your phone, even turn it on at all while traveling an embargoed country if this starts to be applied broadly. Furthermore, it would imply that things like a single BGP route hijack could kill all of a company's accounts on any US service, without recourse. If this would be the case, using any service from a country interpreting embargoes this way becomes an impossibly risky proposition. Which was probably not the intent of the embargo.