Wasn't it Denver's ball because Nashon Wright touched it after the block? If so, the rules weren't rewarding Denver for a bad play, they were punishing Wright for one. If he had not touched it, it would have been our ball. Because he bobbled it, it was their ball.
That's how the rule works, but looking at the play ….
1. Denver failed to get a first down.
2. Denver's line failed on the punt attempt and Denver got their punt blocked.
3. The Cowboys never took possession so it wasn't a fumble (although the rule treats it as such).
4. Denver got a 1st down without ever having to gain the yardage to do so.
Further, under this rule it wouldn't even take a Cowboy attempting to recover the ball for it to work out this way. For example, if the blocked punt shot off into a mass of players just across the line of scrimmage and inadvertently hit a Cowboy first then Denver could jump on the ball and get a 1st down by nothing more than pure luck. I'm not a fan of a rule that makes it possible to gain a 1st down without having to earn it.