It didn't take long for all the Alliance's top government officials to get updated on the situation once their border sensors determined that it was not a ruse, a prank or a false signal. There really was a massive army amassed outside their borders, and the only two groups that they could possibly be gathering to attack were the humans and the Alliance.
Both of them were lousy options, as the human's Galaxy was too close to the Alliance to ensure their safety if there was an issue.
The Cathedral Ships' fleet was massive, and they weren't sure that even the mighty armies of the humans could actually defend against something like that. The thought had the Alliance leadership in a panic, just as much as the idea that they might also be a target.
If the humans fell first, then they wouldn't have them to call on as backup if they were attacked afterwards, but their agreement didn't mandate that they would get involved in a situation between the two groups.