A single defender at the breach also changes things a lot, as we both know since we both have been on both sides facing each other and trying to gain position of the breach for our teams. And it is a second layer, so there is plenty of time to react to anything sneaky around it, respawns arent that long.
If it was a bigger spot, I would agree, but it is a place where attackers can only get in one at a time, which makes it much less useful in terms of being something other than a situational option. A force assault using it is not viable as you have to cap the first flag beforehand, which will not happen if you have a medium group at another flag altogether, and a small group capping can be prevented by respawns (and its not really sneaky as you can see it easily from the top down view).
My point wasn't so much about sneaking in, which is a valid tactic, as there are plenty of backdoors and other hidden sneaking routes to flags in other maps, but rather that once the defenders are on it, the attackers are left with a single way in. It is then that having another way in (going through the window or some alternative) becomes important, as it disrupts the easy hold that the defenders set up otherwise.
I understand that i twas unintentional, but sometimes unintentional things turn out great, like imo this one and there is no real need to remove it.
As I see it, it is not large enough to be a real issue, but as it exists it gives a useful way to break the stalemate in the other single chokepoint.