Players have been able to jump into enemy keeps for years. At the same corner you are showing in your picture for example. There are plenty of other places and keeps where you can do it. Now that might count as an exploit, but this one? Idk. It might be annoying and stupid, but it's not really game breaking.

Just like the people running around big rocks, "using the terrain" until nobody can (or wants to) follow them anymore. You might not be able to kill them, but they don't really do anything except from being annoying.

The sad part about all of this is that we are usually not allowed to show pictures like yours in this forum, because of naming and shaming. And we are not really allowed to talk about most bugs and exploits at all. Because apparently more people would use them to their advantage if we were allowed to talk about stuff like that openly. But without public attention, the devs don't really stress dealing with these problems. So some questionable things stay in the game forever, because of a very ineffective reporting system. And people who paid attention in history classes might know that trying to deal with uncomfortable truths in secret and behind closed doors can become a very nasty problem on it's own.

So instead of banning players for "playing the game wrong" i would prefer to be able to talk about issues openly, so they will get fixed, or at least someone acknowledges that it's just a normal part of the game. So we don't have to be afraid of the ban hammer (aka death sentence) hitting us for stuff we might not even know we have done wrong.