Is Herod's Ignorance of Micah 5:2 (Re Bethlehem) Plausible?

Micah 5:2 (RSV) But you, O Bethlehem Eph'rathah, who are little to be among the clans of Judah, from you shall come forth for me one who is to be ruler in Israel, whose origin is from of old, from ancient days.

Matthew 2:4-5 assembling all the chief priests and scribes of the people, he inquired of them where the Christ was to be born. They told him, "In Bethlehem of Judea; for so it is written by the prophet:” [they then cited Micah 5:2 to Herod]

A few years back I had a debate with a fairly well-known atheist (active online), who claimed that the biblical portrayal of Herod the Great in relation to the visit of the wise men has Herod "acting entirely out of character and implausibly in not knowing the prophecies predicting Jesus." I will now show how this is most likely not a true report of Herod's state of knowledge. Is it impossible that Herod might not know the prophecy of Micah 5:2? Is it rationalizing or stretching the known facts to believe this about him?  Not at all. He was a very secularized Jew (there are many of those today as well), as a Jewish scholarly article noted:

In his recent book The Herodian Dynasty, Nikos Kokkinos portrayed Herod as  Hellenized Phoenician whose Jewishness was superficial, resulting from the conversion of Idumaea by John Hyrcanus . . . Herod’s departure form the Jewish ethos is manifested by his own deeds contrary to Jewish laws and customs as well as his strong cultural inclination toward Rome. . . .

This impression is nurtured mainly by Josephus’s accounts. (“Herod’s Jewish Ideology Facing Romanization: On Intermarriage, Ritual Baths, and Speeches”, Eyal Regev, The Jewish Quarterly Review, Vol. 100, No. 2, Spring 2010)

That doesn’t strike me (to put it mildly) as the type of Jew who would be all that familiar with a messianic prophecy like Micah 5:2. Maybe he was. But if so, this has to be shown by some convincing argument. The above — as far as it goes (I couldn’t access the entire article) — certainly doesn’t suggest a high likelihood that he would have been. 

In light of the above information, I don’t find it implausible at all that he didn’t know about Micah 5:2. And not being familiar with messianic prophecy in general, he did the logical thing a secular Jew would do: ask the religious Jews (priests) in his court circle about it, just as irreligious Jews today would ask a rabbi about some point of Judaism, or ill-informed Catholics might ask a priest about something "religious." It’s completely plausible. Yet my atheist friend assumed it wasn’t. Why is that? Maybe it's because he “has to” be skeptical about everything in Scripture, even when there is no clear reason to be?