No need to refute it. Simply ask them for evidence of their claim. They won't have one because "it's Haram to condemn crimes committed by Arabs" is simply incorrect and completely against the teachings of Islam. NO ONE is exempt from criticism and condemnation of crimes (we're not talking about individual sins here)
Nabi (s.a.w) said that even if "Fatimah, the daughter of Muhammad was to steal" her hands would be cut according to Shar'ee law. Is that not sufficient to say that who are leaders in comparison to the most beloved daughter of the Prophet? If they talk about losing Imaan then remind them of the Hadeeth: "whenever you see an evil act stop it with your hands, and if you are not able to do that then speak out with your tongue and if you are not able to do that hate it in your heart and that is the lowest form of iman." (Sahih Bukhari and Sahih Muslim)
Why choose the lowest form of Imaan when you are capable of speaking out against the crimes?
I respect the need to keep the discussion of Tableegh away but when your question was posed as Tableeghis making these claims then how can you expect the people passionate about Tableegh to stay quite? You should have said "some local brothers claim" without associating the claim with Tableegh if it's not related.
[quote]2. This thread is not talking about each and every Arab, rather those who are violating Shari'ah in the way that is harmful for the Ummah.
You should paste this after every post that brings the topic back to "all arabs"