I do want to gently call into question the danger of the attack surfaces that you have (I think accurately) spelled out:
1) "Doxxing with calls to action (that — and trust me on this — people DO act on)."
For the most part, high-profile "targets" from the troll's perspective are already known to the public anyway.
Those that aren't, and who want to stay anonymous, have a big job doing so - not just from trolls, but from the NSA and corporate advertising culture.
2) "Swatting (look it up). That nobody has yet been killed in one of these “pranks” is surprising. It’s just a matter of time."
This is purely a political problem. Clearly there's a flaw in the system when police can enter a home by the say-so of someone they haven't verified to be in that home. A sensible solution here is to work to abolish (or nearly abolish) so-called "SWAT" teams. For those that remain, obviously their standard of probable cause needs to change so that the scope no longer includes phenomena that are so easy to defraud.
3) Physical Assualt
In a general sense, this is already illegal under law that is widely supported. It's worth adding sexual assault as well.
The example that you give, which is disgusting of course, seems solvable by some kind of client-side solution that prevents machines from activating photosensitive epilepsy.
At the end of the day, there's not that much that somebody can do from a world away. To the extent that there is, I assert that the solutions are largely political, social, and cultural.