It isn't without risk, but when is the last time a US billionaire faced real legal repercussions for anything? US law is 90% based upon being able to outspend your opposition, and if you lose despite outspending them, it mostly involves paying some money, which they already have plenty of by the fact that they outspent their opponent. Even if you are fighting the US government, they government isn't willing to spend endless amounts of money for prosecution. Only if you can't afford the legal costs to keep trying will you face jail time, like the poor.
Plus, when it comes to important communications, the weird, hacked, Israeli Signal fork already has access to these documents anyway, even when they don't accidentally add a journalist to the group chat.
If we're talking summaries of government communications, that's more Microsoft territory, who don't even bother adding proprietary E2EE implementations to their chat software.