Few things come to mind when I see this scene.
1. They are not all terrorist
2. They can be grateful to people who helped them/their country. Fewer people are like that these days as gratitude is a rarer quality.
3. They can gather to celebrate. Such gathering would not be permissible here? Well sometimes even wearing same political t-shirt can get you into trouble.
4. It is amazing America can accept such diversity in culture & race into their country and I noticed after sometime the younger migrants becomes socially & culturally integrated. It is something that makes America great and imbedded in it's Constitution.