I read it differently, especially in light of Schrems II. EU-datacenters from any of the big US-based providers does not automatically make you comply either.
Imho, as soon as you do business with the US or trade in US Dollars, you need to play nice with the relevant authorities.
If I understood it correctly, Hetzner is now "infected" in the same way as the three US cloud providers are. The Schrems II verdict and Cloud ACT basically concludes that no European company can exist in the US and vice versa without having to deal with the same pesky legislation.
An alternative could of course be that Hetzner created a new US based company where the EU parent Hetzner company only holds a minority ownership in the new US-based company. The EU based parent company in turn then "sells" its technology to the new US company. This way, the arrangement becomes more reminiscent of how IBM has sold its mainframe to European companies...
Why would it matter at all if it's a minority or majority stake in the ownership of the US subsidiary?
As far as I understood it the combination of GDPR and CLOUD act only disallows the combination of US mother-company with EU subsidiary, but the inverse should be fine, since the US has no legal influence over the parent company?