CFRC is operated by Bombardier, they have their own staff that does the dispatching for the corridor from Deland-Poinciana (just south of Kissimmee), as well as operate the trains. Now that SunRail is operating revenue service there will be a certain learning curve as the dispatchers learn how best to route trains to cause minimal delays to all parties involved. However, it is very explicit in the contract between FDOT and Bombardier that priority is to be given to SunRail, then Amtrak, then freight. If the dispatcher doesn't have track space to do anything but run Amtrak behind a commuter train, the commuter train will have the priority. Now, that's not to say that Amtrak can't be run around SunRail if there's room to make the move and won't cause delay to SunRail, that's perfectly fine. But it will likely take time for the dispatchers to figure out what moves will and won't work. With as much media attention as SunRail has on them now, being delayed by an Amtrak move would not be good PR for them.
As far as I know down in South Florida things are still dispatched by CSX (minus the bridge over the river south of FTL), but owned by FDOT (CSX has the contract for maintenance and dispatching). The Dispatchers that are on that territory have worked it for years, so they probably have a bit more knowledge on how to finesse things to cause minimal delays to both Amtrak and Tri-Rail.