Tim Murphy is very similar to Rick Santorum politically-- a bit weak on the union and compassionate conservatism type issues, solid on everything else. I really can't see why they don't like him, particularly when they endorsed the corrupt old b*st*rd John Murtha over a solid conservative challenger in his last election (2008).
The best I can figure is that they are a libertarian paper and maybe smoke just a little too much weed from time to time. I've never seen them print anything critical about Ron Paul, for instance.
The Trib is big on population control/birth control things, so Santorum’s Catholic values on reproduction are not what they want to support at all.
To put it more succinctly, the one thing the Trib is not is pro-life.