The Vilna Gaon writes that Achashverosh uses the word “yikaro” (“his glory”) because if Achashverosh were to have said “gedula” (“greatness”) as in Esther 6:3, Haman would have known that he was not referring to him because he was already made great (Esther 3:1).
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.