The Ralbag and Malbim write that Achashverosh was still speaking to the guards, and was asking what motivated whoever this was.
Eshkol HaKofer notes that Achashverosh uses the phrase “fill his heart” because committing genocide requires planning and conspiring that must have occurred right under Achashverosh’s nose. It must have contained a person’s full heart and imagination, and was not spur of the moment.
Yad HaMelech says that whoever is planning this seems not to know that Esther and Mordechai saved his life.
The Eshkol HaKofer writes that if Achashverosh had not commanded artificial respect for Haman, he would not have received it organically. Either the people did not like Haman, as we shall see below (6:3), or as the Eshkol HaKofer suggests, they saw him for what he truly was.
After all, the Yalkut Shimoni and the Targum Sheini write that Haman was originally a barber – a low position in Persian culture as it implied, besides cutting hair, more menial tasks like removing warts, bleeding, etc. A person would hardly bow to such a person in those times unless commanded otherwise by the crown.
The M’nos HaLevi notes that the word “chein” (“so”) used here to describe the king’s command, has the gematria of 70 (20+50). Again, this represents the peak of Haman’s power because that is how long he was in power.