I'm very familiar with that case - would be good to get an adjudication in which the point is properly argued!
There was another case recently in Merton where a similar argument was rejected but this one seems stronger as there is an actual gate to act as a physical barrier to the junction (or at least there was back then).
As this is a TFL case the video is only available on demand so please could you call them tomorrow to request it? They will post it to you on DVD, and usually put the case on hold for a couple of weeks while this is sorted out (but check about this when you call).