A great question. To be honest I really don't know. I think the basic idea is to initialize permanence values very close to synPermConnected so that a small number of learning steps could make it disconnected or connected. We did some experimentation on this a long time ago but I don't recall why this particular scheme was chosen. There are so many small choices like this that are made but could affect performance. This would be a nice little study for a new person who wants to understand the spatial pooler in depth. For now I suggest we leave it as-is (I'll put a comment in there) but maybe we can create an issue for studying this and put it on a newbie list?