The "bandwagon" was not attatched to McCartney because of the community his killers were from.
I don't think his murder was even repoted here.

The big story was that his sisters, in defiance of IRA intimidation, claimed senior Sinn Feiners were involved in the subsequent cover up, and large numbers of Short Strand Nationalists were (briefly) prepared to take to the streets to support the family.

If UDR politicians were accused of covering up the loyalist murders the outcry would be the same and comparison could be made.