Telling the Pakistani's that your sorry a political leader has been killed seems alright. However, it does seem he's hedging his bets about who's behind it. I'm inclined to side with Fred on this. It is much more likely that terrorist scum are behind this than govt. forces.
How about this... the next time someone close to you loses a loved one, tell them "I apologize" rather than "I'm sorry", and see their angry and puzzled reaction.
Offering an apology where he should have offered condolences is completely tone-deaf, and probably speaks more to his underlying instincts to blame the US than to express sympathy.