Thanks for replying. I’ve written to TfL stating my thoughts on the matter.
It is true that the dotted line is ‘under a 10 minute walk between stations’ but in this case, Manor House is also depicted as an interchange blob on the map. Interchange with what? Harringay Green Lanes is the only answer, so logically it should follow that just as with any other interchange, this should allow continuation of a journey. I’ve also stated this to TfL.
Let’s see what they have to say