Did they think it would bring in people? I was always under the impression this was meant to keep people in the park longer ($$$) and add capacity for Guardians...not sure what the original pre-COVID timeline for this was though to be fair.
I also have a hard time believing Disney is making any sort of mistake with their opening date. They’re pushing their park reservation system for a reason, and I’d imagine attendance/staffing forecasting that comes with this system has a lot to do with it. I’d imagine October is the next time they either a.) predict a lull or b.) will expand their capacity, in which case they can test the waters with how a new ride does in COVID.
ETA: I’ve been on the Ratatouille ride and it was super underwhelming, and that was BEFORE I’d been on Rise of the Resistance of Mickey’s Railway (which I’m not too fond of either tbh)