But Iftikhar was never sacked, so where you got this idea?
Actually on 3rd Nov Constitution was put in abeyance and PCO (Provincial Constitutional Order) was issued. All judges take oath to work with prevailing constitution as they work on constitutional laws prevailing at the time of judgement. Thus, once PCO was issued, Judges needed to take new oath under PCO. Many judges did not wanted to take oath on PCO and that means they were unwilling to work according to prevailing laws of the time (under PCO) and because of that they automatically became unfit for office thus loses office (assumed as judges who decided to not work). This is the reason Iftikhar lost his office and not because he was sacked.
Why Musharraf did not sacked Iftikhar? Because, however ridiculous, SC stopped SJC from investigation and that means all allegations on Iftikhar even true could not be investigated by SJC. Even though it has happened regularly in past, constitutionally a Judge should not get sacked (removed from office) without such investigation by SJC. That is what happened with Iftikhar due to his Bhangra on road and getting illegal judgment from SC, that SC stopped SJC from investigating Iftikhar, and thus stopping constitutional requirement that an alleged corrupt judge should get investigated to determine if he/she is corrupt and than only he/she gets sacked. Since President Musharraf was decent he followed this rule and did not took any step, rather let him assume his office, else if Musharraf was like Ayub, Zia, Bhutto, Nawaz, BeNazir etc … than he would have sacked Iftikhar humiliatingly without even sending reference to SJC (as all rulers in Pakistan did in past).