C.J. Karamargin isn’t the first congressional staffer to cross the partisan aisle, but some Democrats are shocked this former staffer to Democratic Rep. Gabrielle Giffords is working for the new Republican congresswoman in Arizona’s 2nd District. On Jan. 9, in a hiring coup, freshman GOP Rep. Martha E. McSally announced Karamargin as her new district director. Karamargin was communications director for Giffords at the time of the Tucson shootings before handling media relations for Pima Community College. The timing of the hiring — just one day after the four-year anniversary of the Tucson tragedy — also gnawed at still-raw wounds...