It really has nothing to to do with the flight controller. They are just saying that they have not actually tested with that one.
If the firmware loaded supports Mavlink and has the correct set up it should work.,
That page is out of date as far as TBD:
You might consider buying one of the cheap ones to try out:
That’s incorrect. A gimbal claiming “Mavlink” support gives you no indication that the gimbal will work with a particular flight stack.
Changes in mavlink over time and mavlink differences between ArduPilot and PX4 mean that you have to know specifically what mavlink version/messages/microservice is implemented by the gimbal, and what firmware it has been tested against.