What is “the tyrant’s plea” (394) in Paradise Lost Book IV?

Reading this quote in context, it comes after Satan has
mounted the tree and has seen with wonder and despair the form of Adam and Eve, in whom
"so lively shines... divine resemblance." As he sees them he plots their downfall and
declares that "Hell shall unfold / To entertain you two." However, at the end of this
speech he seems to offer the "tyrant's plea" to excuse himself for his actions in
planning the downfall of the pinnacle of God's
creation:

And
should I at your harmless innocence

Melt, as I do, yet
public reason just,

Honour and empire with revenge
enlarged,

By conquering this new world, compels me
now

To do what else though damned I should
abhor.

This, I think, is the
"tyrant's plea," with Satan being the tyrant, yet feeling the need to "excuse his
devilish deeds" by saying that he is compelled to pursue his plans to corrupt the
innocence of man, although if he were not "damned" he would "abhor" such a plan. Satan
as a character is absolutely fascinating in this entire epic classic, and the way he
presents himself is worthy of discussion. Here we see his apparent need to excuse his
behaviour. The reference to a "tyrant's plea" almost appears to be paradoxical, as
tyrants by their very nature do not make pleas, thus adding new levels of complexity to
the character of Satan.