At that point in his speech he was thanking people. He got off on a bit of a tangent when he thanked his friend Mark Burnett, producer of the Apprentice, for his introduction. It was a humorous anecdote, he jokingly asked everyone to pray for Arnold and the show's ratings.
See for yourself if you like, skip to 2:37 for the moment in question.
These posts rate right up there with. "Child Trapped in Refrigerator, Eats Own Leg to Escape."
Celebrity president makes stupid pop culture feuds a priority: surprised?
The man may have money, but he has no class and he has no filter for what is and what is not appropriate to say at any given time.
Trump is a master marketer and is doing everyone a favor, including Arnie, with this type of rhetoric. It keeps everyone interested and coming back to see what will happen next on the apprentice and at the WH. It's a win/win for everyone.