It's not that hard to believe that Triple H said that comment about fuck him if he doesn't want to do business we'll do business for him considering HHH said he said that himself. Not gonna say it was the deciding factor or anything but I can see HHH being Shawn's boy and all pushing the issue.
If the Screwjob happened in 1999, I might believe that. But that was 1997 when Shawn was the king of locker room pull and Triple H was just his lackey... barely coming off a year-long punishment for the Curtain Call incident because the other 3 guys involved, including Shawn, couldn't be punished. The idea that Triple H could have been even moderately involved in Montreal is laughable. I've heard Triple H say that it was his call too, but I doubt that's something Triple H would have a problem taking the fall for to protect Shawn's new image. If it were made public that it was Shawn that said "Fuck him!", it might be hard for fans to accept his "Texas Jesus" persona and even harder for Bret to forgive him. I seriously doubt Triple H cares the slightest what Bret Hart thinks of him and doesn't owe him anything, unlike Michaels.
Of course, this is just my own theory, no way I could actually back it up with anything more than speculation, but I just have a seriously hard time believing Triple H had anything to do with Montreal.