Mistral isn't exactly some decade-long state funded national champion. Its a 1 year old startup whose core staff all come from American tech companies. With 0 revenue and minimal market share, there's like no conceivable metric in traditional antitrust theory to block this. Yet the EU prevents it from taking foreign investment all the same.
Look at TSMC in comparison. It IS the national champion of Taiwan, yet its majority foreign owned, doesn't stop it from underpinning the Taiwan economy and spawning massive ecosystems in its local areas.. Taiwan's government understands its place in the international economy, so prefers to cooperate and trust its international partners.