First of all: I’m not American but let me recapitulate the facts as I understand them.

1. Foreign actors are actively and successfully waging war against American democracy (and therefore against the USA and it’s traditional allies).
2. Elon Musk, an American citizen, knows about these attacks on his country but allows them to continue and even supports the attackers by shielding them from discovery.

Shouldn’t there be some kind of legal action to stop and punish him?

No it’s not. It’s a gGmbH. Notice the leading “g”. It’s a nonprofit company.

https://de.m.wikipedia.org/wiki/Gemeinnützige_GmbH

Unfortunately there is no English translation of that page on Wikipedia.