Theologists have long pondered over this verse, since it is at odds with the rest of the Chapter. A couple of things have been proffered, but I have neither the time nor inclination for debate or dispute.
1. Some Bibles use the tem Holy Men instead of Saints, probably meaning the likes of Joshua, Josiah or Jeremiah from the OT. But similarly that could not fit since Jesus was according to scripture the first fruit from the dead.
2. The text uses the word �bodies� perhaps this could be taken as a spiritual body rather than a mortal body.
3. The use of �resurrection� is also curious, but perhaps when translating from Greek they substituted the word egerais meaning �awakening from a sleep� or �arising�.
As you have said yourself it is probably symbolic - and quite likely added after Mattew had written his script.
As regards Herod, he was known as a vicious and cruel man. Herod�s infamous crimes were many. He put to death several of his own children and some of his wives whom he thought were plotting against him. Emperor Augustus reportedly said it was better to be Herod�s sow than his son, for his sow had a better chance of surviving in a Jewish community. Bethlehem to the Romans was a small town at the time and insignificant, the death of say 20 or 30 babies in such a place would quite easily been uneventful enough to be recorded.