Don't know with 3 different manufactures of MH never had any issues with transferring from or to shore power and never had to disconnect anything to do so. But as everything else we have found on these forums if you are comfortable doing something a certain way continue to do it that way right or wrong doubt you will hurt anything.
I'm surprised the gen set manual doesn't recommend a warm up before putting a load on it and a cool down before shutting it down with no or very little load for several minutes. I know my boat generator manual suggested both. I'll check the manual sometime today.
2015 Entegra Anthem 450HP-1250ft lbs of torque
2015 Jeep Grand Cherokee
Roadmaster Falcon 2 All Terrain
SMI Air Force 1