This "young man" is the son of an MS and as far as I can tell, none of the elders in the hall have anything against him. His sister misses more meetings than he does in fact. This bro works the literature counter, sound, etc. There should be no reason for him to be denied from going.
And yes, there are International District Conventions held around the world, including here in the United States. I know for a fact that about 3-4 years ago in Texas, Houston was one of the designated cities. Our hall had the "honor" of housing some of the delegates from South America. And I believe this year, Houston is hosting once again. The delegates arrive via bus at the Rosenburg Assembly Hall where they are picked up by the families that house them.
As Gumby brought out, anyone can attend these assemblies. But it is frowned upon by the Society for ones to just up and go. As long as the Society disapproves, the sheep will meekly follow along and obey.
If I was the father in this family, I would take my son with me regardless. Beats leaving him at home so he can fornicate with the neighbor girl.