I like what you are getting at @orulz so let me try and add my two cents. Although these are guesses, I do feel like financial incentives are a key driver here.
From my perspective, you have a couple of moving parts here; The Omni Hotel, the RCC expansion, and RHA. From what I’ve seen by paying attention to all this stuff is that it would NOT be a good move to expand the RCC without having that 500-room hotel, preferably from a higher-end brand. Without it, we wouldn’t land large conventions to fill the space and this is a bad use of public money.
Chicken and egg situation, of course as a large hotel isn’t going to be built without reason to fill it so they’d want some assurances of a commitment, like a larger convention center. We know that the city (county maybe?) has given Omni some financial incentives, I think even paid for some pre-development work, to open up. I am guessing there are deadlines in those contracts here.
Working backwards, the Omni and the RCC expansion, ideally, need to open at the same time or at least around the same time. Therefore, with some contracts already signed with, I bet, some delivery date in print, that is why we cannot delay here.
So, again guessing, working backwards, when you consider a date, let’s say 2028, that the RCC and Omni need to both be open, and you consider construction schedules, you can see our construction window here for moving the RHA.
On the other end, we all might think that we can just skip a concert season or two or three while we get the amphitheater right. I don’t think anyone wants to play with the small businesses futures as well as Live Nation skipping over us and all the momentum that was built since the RHA has built since it opened is now gone. We’d have to start from scratch and go through that pain again.
Just offering my take here that the window seems very small. Could the city have handled it better? Sure, but I think the main drive here is probably the deal made with Omni and the domino effect it makes on the RCC and now RHA.