Watching it again, that play isn't terribly different than what happened against Samford. Similar route. Similar throw. Similar screw up.
Difference, of course, is the Mercer player just dropped the ball. Samford's player caught it, and then had it taken from him before hitting the ground.
In both instances, the ruling was a catch. In neither instance did the offensive player actually catch the pass.
Perhaps the conference officiating committee should emphasize this play. Referees are typically looking at one area of the field, and it could be that line judges are just looking at the wrong thing. They don't see the non-catch in real time.
Of course, none of that explains overturning the call on replay and then overturning the overturn by misapplying a rule. That just made a bad call into a travesty of the game. If you are going to miss a call, just miss it and move on.