EU have already ordered Facebook (and others) to restrict data sent from EU to US. If US started banning EU tech companies (like China are doing) then it would of course make sense for EU to do the same to US tech companies.
This is of course unlikely to happen as EU and US fairly operate in the free market.
Europeans are free to say the same, or negotiate acceptable GDPR-style data protection standards with the countries that receive their data (which in many cases has already happened).