I'm okay with anyone else getting involved/sticking their nose in to the whole mess. As it is even if people don't know the actual cause of the ice cream shop getting destroyed, Rin will eventually have to come out and say "Yeah that was me, Roxas, and Riku dealing with Vanitas" after his friends are murdered.

And even BEFORE that chances are he's going to be tearing through the city on fire chasing after Vani, sooo...