As I mentioned in a previous post, I am sure there was a reason this gentleman was served his tea in a paper cup. For instance, at my airline our policy is that if a passenger requests a tea or coffee on descent we serve it in a paper cup. This is because you cannot have china cups bouncing around the cabin on landing, but a paper cup is allowed. The same thing happens on departure. The passenger gets his/her champagne or orange juice in a glass, but if they haven't finished it prior to pushback, we transfer it to a plastic glass.
This gentleman complained that he was served his morning tea in a paper cup. I suggest he probably slept until the last minute and then when he requested tea it was close to descent. The crew on this flight did just what any crew on my airline would do. They accommodated his request, but due to the fact that he may not be finished his tea prior to landing, they served it to him in a paper cup.