extend the half or enforce to start the 3rd qtr

[MJT]

Same state championship game as my last post. On the last play of the 1st half there was a dead ball personal foul by the defense. I was thinking, extend the half, but they said "DB personal foul against the defense which will be enforced on the 2nd half kickoff."

3-3-3a says "A period must be extended by an untimed down if during the last timed down there is a foul, other than USC or nonplayer, by either team, and the penalty is accepted.
I know a DB PF is administered from the SSpot, but it was not a USC or nonplayer, so shouldn't the half have been extended for one untimed down after the penalty enforcement???