In the books it is insinuated the Commander was actually a high up military leader in the war which is supposed to have preceded the events of the book, and he and Serena Joy are much older/middle-aged, so his presumed high standing (which is actually revealed in the epilogue) makes sense.
I haven't really liked the way they decided to portray the Commander and Serena Joy sympathetically in the first series, and I remember on these threads last year some people really fell for it.
However, the way they have now revealed him to be nothing but a lionised terrorist thug is really clever. The series hasn't really explored just how much some men benefit from the patriarchy (Nick doesn't really does he?), but this thrusts into focus just how spectacularly well some men do by being utterly vile and oppressive.
It shows just how good the screen writing is and also just how prophetic Margaret Atwood was in the 70s that she wrote a character who embodies the patriarch so utterly timeless.