Guild Wars 2

So today i was in our boardrelands and kept seeing redvale under attack. So I ran down to see what was going on, to not get bested, but trolled by an exploit imo. In this video you will see the player retreat to Spawn area below a rock and claim the buff, while still being able to attack us unharmed.

Today happened the same thing on RoF server. I was wondering which option should I select when report players abusing of this glitch.