The Deliberative was structured to prevent the Solars from marching on one another and further space-time shenanigans like the Time of Cascading Years. As a result, its power structure was decentralized to the point that individual Solars didn't even need to be a part of it. I think something like changing the entirety of existence would've seriously freaked out everyone in and outside of the Deliberative and kicked everyone's paranoia up a notch. If it was done once, it can probably be done again. Who knows what the next reckless Solar with an agenda is going to implement without consultation?