A mechanic told me that the rear wheel on the drivers will not turn by hand on my 98 Durango while attempting?

to give it a wheel alignment. He said the rear wheel on the passenger side is okay. So I thought this to be a little strange and said okay I will get back with him. A friend of mind told me that since you have 4x4 you will have to put the truck in neutral first and turn the wheel. I tried it with my friend and it worked. But what bothers me is that this is a certified Mech and can some one tell me if the wheel suppose to turn regardless if the truck is in neutral or maybe the Mech was just having a bad day. Oh yes and he said if he had to take the wheel off on the lift and not knowing what would happen it could cost maybe hundreds of dollars. What do you think.