Harry is no longer on the White Council, which is a member of the Accords. They have cast him out. They seem to be arguing that they can still come at him for breaking the laws even if he isn't a member, which is weird, but they do it to practitioners too weak to join the council so there is precedent.
But what if Harry were to join the accords like Marcone did? Then he would be protected from the Council by the accords, and they can't really claim he's part of their group anymore.
So he would need three signatures that would be willing to irk the council. I assume he can get winters. Probably also Bigfoot's if his people actually join the council like he seemed to be proposing. Ivy? Think he could get Fix to sign for summer if Bigfoot doesn't join? If he's looking at starting an organization and people are going to start to move against him anyways... it seems like being a signatory of the accords might be useful. Maybe make Goodman a permanent retainer, hire the hellhound if he can afford it, get a permanent detachment of winter goons to control, that kind of thing. I wonder if Bigfoot would be willing to take on young human apprentices recruited from the paranet that would fall under Harry's organization rather than the council...