I don't get it either. Never have understood it. The only thing I can figure is that Iraqi Republican Guards were involved, one in particular named Al Hussaini (sp?). The Iraqi's relocated here after the Gulf War in an agreement with the George Herbert Bush administration. The deal was that they'd stand down during the war in exchange for being permitted to relocate. (I'm going on memory here and read the book a few years ago)
About 6,000 former Iraqi Republican Guardsmen moved to the US after '91. If it was proved (and I think it easily could be proved) that an Iraqi Republican Guard helped plan and execute the OKC blast that killed so many children, it would ruin the GHB legacy forever. So much as GWB protects Clinton, I think he is protecting his father as well. They all protect each other.
You could be right about that assessment.