You're right, there's no existing solution to exempt US citizens from these exploits. However, with the massive resources available to them, if they focused on enhancing our security rather than fouling it, I very much believe we would be better off. Think about how much crime occurs in the modern era through electronic hacks and exploits. Would it be better to have these intel back channels, or to stop these crimes? Their priorities are in the wrong place, through tradition more than anything else.

There are many, many platforms that are "occasionally used by adversaries". The Intelligence Community has put exceptional resources towards one that has a very significant market share among it's citizens. And given the wholesale surveillance we are already under, I can't accept that this was an innocuous decision.

Trust is built through positive actions over time. I have zero trust for our Intelligence Community as is; and I've actually worked with US intelligence. If they devoted a majority of their efforts to finding and patching security risks through public and open source means, I would slowly start to trust them again.