Even McDermott at his postgame press conference, when asked about the defense, was all "when you take away the blocked punt they only gave up 16 points." And as you know he's not a guy into excuse-making or fudging numbers.
When you're discussing the DEFENSE, not the TEAM but just the defense, it's perfectly logical to filter out non-defense points allowed. It's like when you want to know how accurate a quarterback is, adjusted completion percentage that filters out drops is more accurate and useful than raw comp%.