Last quarter Microsoft's gross revenues were somewhere north of $14 billion. If they paid 500 million to Eolas (and presumably it was less than that, given the verdict of $521 million and the fact of a pending reexam that might kill the patent), that's way less than 5% of their revenues for one quarter. Most securities experts would say that isn't material.
And the other terms of the agreement probably amount to saying that Microsoft can do what it used to do. That's not material, either.
Finally, as TFA says, Eolas is not, in fact, public, so has no public disclosure obligations.