It didn't cross my mind to be honnest. Their about page didn't give that impression. Also, I looked up a bit Spencer Scott and I found some decent articles. For example: Solarpunk: Refuturing our Imagination for an Ecological Transformation.
Personnaly, I wanted to find specifics about their decission-making process. I didn't manage to really. I suppose if they had a model of horizontal organizing, they would be talking about it? In the same time it looked like a decent enough project, so it seemed like worth posting.
On second thought, does this project seem to you like it could be a cult?