I want to know what the Senator would gain from an assassination on an already dying - if not already dead - Emperor? How stupid would he have to be? Even if it succeeded, you couldn't stop it getting out that it was an assassination, and the rumblings would be immense across the Empire. Likewise, fail in the attempt and the Senator is finished.
Something doesn't add up here.
Who stands to gain from a successful assassination of the Emperor? Who wants to spark a civil war in the Empire? The Federation are strong candidates for that.
Who stands to gain from a failed assassination of the Emperor, or at least a fabricated "assassination attempt"? There would be no faster way to take down a rival than by smearing their name with a crime so bad, and by uniting Imperial citizens in outrage behind your claim. I think intelligent folks can draw their own conclusions.
Just the thoughts of a Lieutenant Commander from the other side of the fence.
You make some decent points, the situation is extraordinarily odd. Although it is possible that Patreus is overconfident in his abilities due to the successful debt collection efforts with his private fleet, and wanted to hasten the process thinking he would be able to take over the Empire.