That’s why I think San Diego is the best place to put all the Orcas because it’s already the largest facility and has the opportunity to get larger. It also has the largest pod currently in a SeaWorld park. Not to mention the massive backstage facility could easily handle the new orcas + any animals not compatible with the main exhibit.
Orlando actually has the largest overall facility for orcas (seven pools versus San Diegos's five). Although the Blue World Project would be much more suited to San Diego as San Diego has the space to expand their orca facilities (Orlando dosen't).
San Diego having the largest pod is just down to luck. They've always had the most cohesive pod, and thus have received a lot of orcas from the other parks over the years.