"Am thinking, if it was Obi then either Anakin would actually knock out the emperor to protect the friend from the lighting thingies, or even if he didn't then Obi Wan would've still stayed true to the 'jedi way' and just tried to arrest Palps, giving Anakin no reason to attack like Mace did."
Exactly! And that's why Palpatine arranged for Kenobi not to be there!
All the general grevious stuff was just a distraction so Palpatine could get Anakin on his own.