Pretty sure Svenbent = daneblood, so he was referring to the same update you are. It removes the notification to other characters to zone, but not the code to process zone requests, so if any character has the old version loaded you would still be potentially warping. If all characters use that version, it should be ok. A better fix would be to remove the code to *use* the zone request, or both. It's also a bit cocky to put your name on someone's addon for deleting a few lines of code.
PacketFlow is not altering the traffic sent to the server, only the speed of it. Getting rid of PacketFlow won't change the faulty premises I outlined in my last post, but it might make the circumstances around them occur less often.
Using a modification that removes the zone request packet behavior will be fully safe with or without PacketFlow, as that is the cause of the erratic behavior. As said, it does mean you'll typically stop short of a zone and have to nudge your character forward, because being in range of the person you're following while they zone is not crossing the zoneline.
A better fix would be to use a different sort of zone request; send the position and direction so the client can override the default running behavior by reaching that position then running in that direction. Then you won't get stuck at zonelines, and you would have no erratic packet sends either because the client would still handle zoning for you.
It looks like it does attempt to vaguely validate that your position/starting zone are correct but not particularly well. There's some unintended behavior happening and people have apparently been zoning into the wrong areas or ending up in the middle/off the map after the zone. Not worth the risk for what's ultimately a minor annoyance. I personally don't see the need for the addon at all but that's just me, I can't imagine some astronomical improvement over vanilla follow or just setting your follow index using windower/ashita functions.
I haven't used this addon, since I use Ashita, but a low latency follow is actually pretty nice QoL. Because the game only tells the server your position every 400ms[250 with packetflow], and the server does not always update everyone in the vicinity immediately, normal follow can be a bit choppy and tight corners often lose followers. That said, you can improve normal follow considerably by targeting the person you're following(this will force server to update their position every packet interval).
With a follow that processes your position with per-frame accuracy, you don't have to worry about how you run at all because it'll be effectively impossible to 'lose' a character running the same speed you are. The approach to zoning is just really poorly done.