You acknowledge he is no special moral authority.
Neither are you, I'm sure you would agree. Yet you seem more than content to do exactly what he did—make your case through the mediums which are available to you. Jimmy Kimmel doesn't claim to be special. He just has certain issues where he is extremely passionate and that passion comes through when he discusses certain issues.
He is fake crying about an issue he doesn't even understand, as evidenced by saying you don't need an automatic or semi-automatic rifle. If you don't know why that statement is flat out moronic, you don't know about guns. (A general "you")
What possible evidence do you have that he is "fake" crying. Is it not possible that with 58 people dead and 500 injured, that he simply possesses, for example, a shred of human empathy?
As for the rifle statement—why is it that pro-gun people always jump onto the semantics of an argument, not the substance. Did it occur to you that perhaps, he was using the colloquial meaning of those terms and expecting people to understand what he meant, rather than checking the textbook definition of every word to make sure it was used perfectly?
It is plain to see that most of the people who want gun control won't stop with whatever measures they agree upon today, because people will still be killed with guns. The ultimate goal is obviously to take them all way.
This is a large claim. It completely dismisses a fairly large middle ground. Not every country has gun laws as strict as, for example, the UK. The spectrum between "total ban on all guns" and current US law is a big one. Many people see valid uses for guns that are worth the risk of some loss of life, but consider the current level of loss to be unacceptable.
You can even tell during his diatribe that he would like to just start screaming to take all the guns away, but he stops himself multiple times.
You determined this... how? Your advanced mindreading powers? There are any number of things that might lead to a hesitation in speech. For example, he likely wants to avoid venting his anger with a stream of curses. He's also emotional, which is not known to make people eloquent.
Tears don't replace a good argument, which Kimmel doesn't have.
He certainly made a good enough argument for you to come here and be upset about it. It's also worth considering that he didn't make the argument, not because he doesn't have one, but because of sheer frustration. What is the point of making the same argument that has already been ignored more times than anyone wants to remember? More than a few pro-gun control people have grown fed up with the entire debate and feel they are stuck saying "told ya so" as the body count rises because there is such overwhelming apathy towards change.