A lot of people will simply see the headline, assume you're guilty and treat you as such. And a lot of people are willing to treat those they think are pedophiles very very badly (there was a case recently where a murderer serving life in jail killed his pedophile cellmate) Anyone that knows about this incident will probably never allow you to be around kids unattended, regardless of your innocence. You will be a social pariah.
Innocent until proven guilty had to be enshrined in law because most people will treat you guilty until proven innocent, and they don't have much concern about forgetting the 'proven innocent' bit.
"Arrest first, deal with nerds protesting their innocence later" still involves getting arrested.
I would hope that authorities at least would try to build an actual case against you and not just raid your home because of some fraudulent traffic from your IP. I might be too optimistic in that regard.
But if p2p exit nodes were orders of magnitude more common, then the burden of proof would indisputably be the responsibility of the prosecutors, since anyone could credibly claim "someone else did it."
And that's why this trope of "but what if someone does bad stuff on your network?!" is so frustratingly self-defeating: if everyone just ignored that risk, then everyone could have a p2p exit node, and the risk would be mitigated. It's a sort of prisoner's dilemma where nobody wants to be the early adopter of a system that would, on the whole, benefit all of us.
A society is difficult to surveil when everyone uses Tor as both a client and an exit node, and onion routing is the default method of exchanging packets (some might say it should have been incorporated into the original design of the internet). So it's perhaps worth noting that adversaries of society, such as the NSA or FBI, have a great incentive to perpetuate fearmongering about p2p networks and the threat of "but whatabout muh criminals on muh network!"
If you're reading this, maybe it's time to setup a Tor relay (with config flag `ExitRelay 1`).
I think I'm more cynical about our justice system, but the way I see it, this just gives them ammunition to go after anybody on a whim. Simply getting tangled up in the justice system, even if innocent, is an expensive and stressful thing. Most of us do not have the resources to just have a dedicated team of lawyers taking care of everything. So if everyone was running a Tor exit node, and it was known that there was CSAM accessed through some of them, an overzealous prosecutor could probably push through at least a search warrant of your computers because as a Tor exit node runner, there's a reasonable chance that CSAM was accessed via your node. You're not getting your stuff back for a while if that happens.
Are you asking about the consequences of breaking laws while using someone else's internet access as an exit point, or are you asking about the dynamics of CSAM production?
_that comment is giving off really nasty vibes_