I was in military intelligence. I am qualified to make the evaluation I made.
Violent citizens can be dealt with through police channels and public servants, not lawless shadows in the dark in a giant data center somewhere.
How many civilian whistleblowers have there been compared to how many enlisted whistleblowers there have been? I myself once spoke up about an unscrupulous sailor, but I went to an E-8 and asked him for his advice (hey, a friend of a friend is doing something wrong, blah blah) and he pointed me in the right direction to handle it without fucking this guy over, and the behavior was corrected and we all went happily about our missions, no harm, no foul. It's easy to do.
Civilians don't have as much of a moral obligation to the rest of the country, they aren't ready to die to serve it.
Your argument is basically, "well, private sector is going to do this shit anyways" but that's ridiculous to say that we should continue to be complicit in letting the NSA exist just because if we don't let them do it, someone else will.
Citizen's hands are dirty for being complicit, and more people need to realize that a unified effort of enough magnitude could make HUGE cuts to state intel sector a reality, and we could pump that money into better police training, better resources for investigators and people who are invested in their communities rather than some asshole with an xkeyscore login and a name on a screen.
I'm not saying state intel agencies don't contribute to ethical sources like infrastructure and civ eng stuff, of course they do, but it doesn't excuse all the other terrible things they do, and it'd be possible to redirect that talent and those resources into those areas through other agencies.
DOT could offer special hire credits for intel workers with infra design experience, for example. That could be made possible by NOT running $10-digit datacenters full of civilian facebook messages with tax payer money.