Disconnect does need ability to carry MCA just like the conductor. But unlike conductors the disconnect also needs to be rated for the motor load, unlike the conductor it may end up making or breaking the load. This is not quite as straightforward with air conditioning units as they are not marked in HP, but is more clear with general purpose motors as they are usually marked and rated in HP and a "safety switch" usually is marked with a rated HP also.?
Since mca is 23.9 amps the conductors AND disconnect would be rated for 30 amp
While the ocp is the circuit breaker rated at 40 amps.
The disconnect is to be sized as the conductors. In this case a 60 amp disconnect is not required.