I have no problem with Sigil getting SoE to co-publish the game,
fist and foremost because of the reason Brad left SoE,
he was giving to many different titles to oversee and manage,
and felt it was for the best if he left. Only after that did he decide that what he needed,
was to be hands on in a game compared to the managing of many.
This coupled with the fact that he had a contract SoE led him bail out off sounds to me like they are on pretty good foot with eachother.
(not actually quoting above, but it was from an interview)
It seems that Brad was getting run-down by doing something he really didn't like to do.
This along with the fact that everything about development and customer service is still in the hands of Sigil tells me the game is going to be done the way it should,
by the vision of the team working on it and not the money men.