You need glyphed Disengage (which you should use 100% of the time anyways) and you have to jump (which you should do 100% of the time anyways when disengaging).
There's zero reason to do it this way. The timing required is so precise that there's no way to make it consistent, even with practice.
It wasn't fixed with the other's I'm guessing because they can't easily. There is probably a reason they can't simply put up a wall in the way, as that might interfere with how the mechanic to get onto the belt works or how the belt pulls someone off. If they couldn't get it done right away with the other fixes, too much time passes and TOO many groups would be impacted.
If they should have left everyone's exploits in, that's another story. I think they at least wanted to make the earlier progression groups in 25's have to deal with the missile, missile combo late in the fight, which might have been avoided with a constant belt team.