Latency can cause the following things:
1) People appear to be jumping around because you are lagging. (The opposite is true if someone else is lagging -- they will appear to be jumping around, or teleporting from one area to another.)
2) You'll lose certain timed abilities. (I can't tell you how much I rage if I hit a random lag spike and lose Aetherflow. Waiting a minute for my stacks is too long! Doesn't happen often, but it's a known thing.)
3) Pets are slow to follow your commands. (You'll need to spam the button many, many times.)
4) Mechanic AoE/Line circles will appear for shorter periods of time than usual, thus resulting in you DEFINITELY getting hit by that AoE.
5) You appear to get out of an AoE in time, but you don't. (This is when other people see your dead body 'slide' on the ground -- because your client notified the server that you had moved, but it was after the server registered damage... thus, you slide to your death.)
6) Casts/abilities just don't go off.
Please notice how the majority of laggy side effects involving your position being updated are clearly due to packet loss. That's why people appear to jump around when they are lagging. That does not mean someone will continue to follow a straight trajectory, or even run around a while, while they are weighted or stunned. If the video posted displayed the player in question running for another second before stopping for the stun, I'd say it might be lag. If it showed the person being stunned and then 'teleporting' to a spot a few feet away (in addition to the player seeing other people do the same), I'd say it might be lag. I would give the person the benefit of the doubt because 'cheating' is a VERY serious allegation. SE takes it seriously, and they'll do their investigation.
To be clear, no one is threatening to try to break up anyone's static...? (I don't know where that was mentioned. I think most people complaining are people who have noticed this in the solo queue.)
These aren't salty players, either. As I said before, it's only one person everyone is complaining about, and I suspect most didn't see that video before forming their opinion (considering it was just recently posted). I see people complaining about it in PvP linkshells on my server because it's something everyone clearly notices, whether they are paired with the person or not. I personally haven't seen it myself (my job isn't generally to keep the healer CC-locked, and I don't think I've played with the player in question more than a handful of times), but I trust the opinion of a lot of other players I've personally seen in the Feast (on my server or not). They're not salty from losing -- they're annoyed that someone is seemingly circumventing the rules. That would annoy me too.
Anyway, it's worth investigating at the least.