What a fustercluck that was.
First and foremost, this shouldn't have been obstruction. F3 came off the bag and was in the act of receiving a throw (which still exists in pro baseball as an exception to the obstruction rule), so there shouldn't have been any obstruction. That's probably why U1 didn't call it. Until this year, this would have also been nothing more than a wreck in college softball.
But if there was obstruction, it is what pro rules considers as "Type A", since it occurred on the BR before reaching first base. That's an immediate dead ball, and runners are awarded bases that the umpires feel they would have achieved had there been no obstruction. I don't see how R1, who came all the way around from first to score on the play, should have been returned to third. I guess the crew decided that had U1 called obstruction and an immediate dead ball, they would've reasonably put R1 at third instead of letting him score.
I agree from a softball perspective that this would have been a run scored and the BR out at second.