In my opinion there are two perspectives for this. Religiously speaking Hazrat Muhammad (PBUH) had given the right of decision making over any issue to courts. It is another debate that the judicial system of Pakistan is purely western.

Secondly,This system has been passed by the parliament of Islamic republic of Pakistan. Lal Masjid people have no right to arrest any person though he/she is the owner of a brothel or a massage center. If they have problem they must activate the government system by reporting to the police. They have no right to take law in their hands.

Pakistan is struggling for her sovereignty over many years. Announcing a state within the state is a really big challenge for Pakistans sovereignty. Lal Masjid administration announced " Danda Police", Shareeyat courts etc. According to the realist theory of IR prime importance is always given to the National Interest. The act of violence by the lal Majid burqa clad pro-talibans is fully against the national interest of Pakistan.

From where these militants are getting the weapons? this is another question? This kalashan koof culture is the crop of what seeds America sew in Pakistan during the cold war. Another worst effect of Pak-US relations in this context is the prevalence of the Extremism. People of pakistan being the under developed nation are rigid,never changing and strict towards religion.

Lal militants know that they are wrong. They are simply unable to accept that their point of view is wrong religiously, soicially and politically. Government efforts to establish the writ the state should continue.