How does that happen, you might be asking yourself right now? It doesn't. It doesn't happen. We are not talking about a mistake that comes from not having a dedicated special teams coordinator, we are talking about a mistake that comes from absolutely no one on the coaching staff paying even the slightest attention to special teams.
Punt blocks happen, teams get punts blocked all the time and usually it is because of a very well designed, clever punt block by the opposing unit taking advantage of some sort of quirk in your punt protection. That isn't this. Iowa did nothing special here, the outermost edge rusher was unblocked and just ran a straight line. The snap to foot time was under 2 seconds, which is great, exactly what you're looking for, it just got blocked because the punt unit was aligned for and protecting for a punter that wasn't on the field. Those are things that simply do not happen at this level of football and yet here we are.