the author of the article writes:
In my view (proto-Mark as a marcionite gospel), I don't think that Herod was mentioned at all in the original story. But his words of wonder about Jesus's exploits figured. Only, they were not the words of Herod.
But the words of the Demiurge.
The demiurge could have a reason to kill John the Baptist: he failed in his mission: to recognize in advance the Son of Man and stop him.
This scenario explains why Herod was introduced in the Gospel story by the anti-marcionites. Only a king of the status of Herod could work as an earthly 'demiurge'.
I don't see other reasons about why Herod had to be hated by the evangelists: it is evident that in the Real History Herod Antipas didn't persecute the Christians.
Note that the scholar Brad McAdon concedes already that the birth story of Matthew and Luke were anti-marcionite. The Herod/Pharaon who killed the babies is a very good example of how the evil demiurge could work against the Son of the Alien Father ("Bar-Abbas").