Seems you do not know what Kharjee means and why they were labelled as Kharjees by Ali (RA)? … and reason what you mentioned would not work.
Kharjees were a group of people who from outside were staunch Muslims (as far as Aamaal was concerned) but their interpretation of Quran was different.
Anyhow, their interpretation of Quran was not a problem. Problem was that, using their interpretation of Quran, they also started doing ‘takfeer’, that is, declaring Muslims not agreeing with their interpretation of Quran as ‘Kafir’ and also declared both Ali (RA) and Amir Muawiya as apostate (Kafir) who should be killed. It is their this trait that made them Kharjees (or people who left fold of Islam)
Initially, Ali (RA) tried to talk with them and many left their Kharjee group, still a number stayed adamant considering Muslims not agreeing with their interpretation of Quran as Kafir, and in the end battle of Naharwan happened where most of them got killed. Though that was not the end of Kharjees, as over the years, many group of Muslims started adopting same trait as Kharjees, doing ‘takfeer’ and killing Muslims.
In Pakistan we have many such groups who are Kharjees. Difference is that, disagreement is not just on interpretation of Quran, but on Shariah laws and Islam. If people disagree with their interpretation of ‘Quran and Islam’ then these Kharjees would declare them Kafir and would try to kill them.
Unfortunately, most who are Kharjees come from Deobandi and Wahabi sect, but that does not mean these people are Deobandi or Wahabi, as even if Deobandi and Wahabi would disagree with their interpretation of Quran and Islam, they would not hesitate to kill them.
Government could not do much as government themselves are scared of these people, especially political government whose purpose is just to loot and plunder. Army is already fighting Kharjees in the name of ‘war on terror’, but unfortunately army is also infected by people of this group, and thus it is very difficult for army to fight them effectively.
Suggestion that religious scholars (Ulemas) of all sects should do something about it, then that would not work with hard-line kharjees. Only thing is that, if Deobandi and Wahabi Ulema would declare Kharjee’s act as outside Islam (like doing suicide bombing, killing Shias and Sunnis, attacking Sunni mosques, Shia Imam-bargah, Mazars, Milad-ul-Nabi gatherings, etc) then effect would be that, Kharjees would find difficulty in recruiting new men in their Kharjee fold. On the other hand, Kharjees would start killing these Deobandi and Wahabi Ulemas too (that they have already done … killed Ulemas if they find any Ulema of Deobandi or Wahabi sect disagreeing with them).