The congress pattern traditionally has 4 blades on 2 backsprings, and a half-congress will have 2 blades on 1 backspring, and all half-congresses that I've come across have the sheepsfoot large blade and pen small blade. So this knife is definitely a half-congress. I'm guessing he calls it a "pen" because it's slightly shorter than the accepted standard congress length, with thinner ground blades and lighter pulls, like typical pen knives.
Damnit, I really want one of these. The more I look at it, the more I like it.