I put a lot of faith in the FRD manual, since I have to switch codes from Friday to Saturday and for sure... under current NF rule code, team-B can never, ever score points on a TRY down no matter how the ball got into A's EZ.

I would say something like this:

"During the try, offensive holding on [A] in the endzone. Because the penalty would result in a safety, the try is unsuccessful."