Milton wants the reader to understand how this hierarchy works. Beelzebub is the second highest in command, which is why he commands and receives so much respect. While there are other higher demons in Hell, Beelzebub is described in a way that makes him seem more evolved as a demon. The descriptions allude to him being higher intellectually, and looking princely. Beelzebub looks the part that he is playing. While Milton portrays Beelzebub as this wise and scholarly figure, we are still to understand that he is flawed because he is fallen, and everything he says, while enthralling to the masses in Hell, is flawed with sin. He is flawed because we find him in his speech still trying to find away to punish God, something which they could not do. Within the time God is the be all-end all. You do not question God, period.
The allusion to sat is one of that to a throne that Beelzebub and Satan sit upon ruling over Hell. We are given imagery that makes Satan and Beelzebub the king and prince of Hell, tying very much into the description we get of Beelzebub throughout this section and to the classic description of both (Satan as "the prince of darkness"; Beelzebub as "prince of all devils"). Milton tries to draw a connection between the flawed thinking of the leaders of Hell here and the flawed thinking of the monarchs. Previous to the Puritan Revolution it was believed that the king had a divine right and that the king was directly descended from God. Milton, being a puritan and against this idea in the monarchies rule, tries to show how flawed and really how close this hierarchy or monarchy of Hell is set up to how the monarchy was set up in England and shows the similarities between how flawed both parties thinking was.
-Erik Scott