As a "pillar of state", Beelzebub is like a chief counsel to the rest of Hell. Beelzebub is the main speaking parliamentary figure. While he is flawed because he has fallen, Milton creates an air of sophistication and almost godliness to Beelzebub. Milton is still playing off the contradiction between how the demons see themselves (still as angels) and as what they actually are (fallen angels). Beelzebub is different from those who have spoken before; Beelzebub is the wisdom of Hell, if hell indeed can have any wisdom at all.. As a "pillar", Beelzebub is the support for the rest of hell. Beelzebub has received this respect and his position as 2nd in command because he is perceived as wise and stately, as a pillar of state, a pillar of the community. Milton almost gives the illusion that in a way, at least intellectually that Beelzebub is indeed the top of the hierarchy in Hell another contradiction to show that while this Hell has an air of order in reality it has none.
The term pillar is also a term that continues to back up the thought of Beelzebub as a grave, stone like serious figure. Milton continues to use these terms to exemplify the thought of Beelzebub as this stone-faced, stoic, gravely figure.
What Milton continually does however, is use words like seemed, to show the reader that while the illusion is that Beelzebub is this wise, stately figure, he in reality is a fallen angel who is flawed in his thinking. Milton wants the reader to remember that however theses speakers may seem, it is simply a perception but forth by other fallen, sinful beings and in reality they are all mortally flawed.
-Erik Scott