I for one would prefer not to have criminal psychopaths running around on the streets setting fires to immigrants homes.
It seems the police found a reasonable way in this case to identify persons sniffing around the home that was burnt. In my view that's a very reasonable, non-discriminatory question to ask, and possibly it might be the only way to identify the culprits.
If I were those kids and I did it, I'd fess up. Five people were killed. Own it, or live your life admitting you are both a murderer and a liar.