So based on what the patch notes suggested; to me it highlights one of two things about the ability to exploit Guardian (or both) in such a way:

- The "PvP team"/devs literally could not figure out how to go forward or code the ability to not grant a player near immunity from claiming an ovoo in Frontlines situations while under its effect but still let it function to allow potion use uninterrupted in CC for several months on end...

- PvP is still an afterthought even after it's like, 3rd revamp into relevancy and after trying to be hyped up about keeping it relevant this time. So fixes like these are not of any real priority and should be expected to take months to address after their initial theatrics of timely balance/hotfix patches following CC's implementation.
*To piggy-back off the last point, I also find it equally likely that usage of Guardian in this way was not a prevalent or at least not an ongoing issue across the puddle for JP games, therefore not necessitating immediate action in the dev's eyes.

I'm willing to bet that the latter situation is the more likely cause. No matter how much they try to change their stripes, the devs always let PvP fall to the wayside after one patch revamps and "breathes life" back into it, before they stop updating vendor rewards or token rewards for the entirety of the expansion cycle- into the next. I would like for them to prove me wrong, but this isn't my first rodeo with their PvP behaviors. Aside that, yeah, yeah, good for them for addressing this PLD thing. It only took them this long to do it long after people threw their hands up in exasperation from the radio silence.