Re: FBI Arrests Man for Tweeting a gif
I think you're going too wide with it. Mailing someone peanutbutter is not assault, but mailing someone with a peanut allergy an envelope full of peanut dust and a note reading "You deserve anafalactic shock for that thing you did" most certainly would.
If this guy blatantly declared he was trying to induce a seizure, sent a flashing gif that's clearly attempting to induce a seizure and says "YOU DESERVE A SEIZURE" on it, then he is asking to be made an example of and we should oblige.
To prevent the issue from going wide, as you describe, I think it needs a few barriers of checks and balances, but I think we have that in place already within the justice system. It's a slope, but it's not slippery. I Would not expect any asshole to be able to send me to prison because I post a funny gif just because this guy goes to prison. It doens't get rid of juries that need to be convinced or defense attorneys that can show it to them.
Nowadays when people start to get killed by fireballs, no one says they need to dodge the fireball anymore; they say they need to go get a fire resist ring and some ice damage so they don't have to.