There was an article from Ross Dellenger where Kirby Smarted was quoted as saying that Matt Loeffler told him the F reported the foul on the wrong team. If that is true, I interpret that to mean the F intended to report OPI and just got in a rush and got his numbers/teams mixed up. That seems plausible to me, except for the fact that if it was the case, F should have immediately went to Loeffler after the announcement of DPI to correct himself. The fact that this didn't happen makes me think the F saw how bad his call was on the video board and decided that the fallout from getting downgraded after the game would be worse than backing off his call on the field while he still could (since the fans' behavior bought the crew extra time).
I just missed seeing this in real time, but I have seen the broadcast video of the entire event, and would agree that, based on what I saw of the 'reporting' of the foul to the R by the F, there was, indeed, some confusion about the guilty party. After observing their interaction during the reporting process, I truly believed the call was going to be OPI. I was quite surprised by the DPI. So, I am not surprised that, once the announcement was made, and the crap got thrown on the field, yes, the F may have had a chance to see the replay and realize, "Oh, wait, that was the offensive player that shoved off, not the defensive player. In that case, the shove off didn't affect the defender's ability to intercept the ball - let's pick this flag up."
I have no facts to support this conclusion, and I am only speculating, having been in similar situations in the past, and made a similar mistake once (although I recognized my error almost immediately, and quickly corrected it before it became a major problem). So, I could be WAYYYYYY off base. We may never know what really happened. But, I think that is a plausible explanation.