Illegal Forward Pass

[Grey Hare]

I know this subject came up somewhere on this board before, but I wanted to revisit it concerning Illegal Forward Pass.

On the NFHS web site, it describes the illegal forward pass play as:
Team A has the ball first and 10 on its own 5 yard line. A1 drops back and intends to throw a backward pass to A2. The pass is actually thrown forward. A2 then throws a forward pass that actually falls incomplete.
RULING: Illegal forward pass. If the penalty is accepted it is enforced from where the illegal pass was thrown. Since that spot is the endzone the result is a safety.
Ok, I've got no problem with that so far. But, then it goes on to say, If the penalty is declined the down counts and the result is a safety since the end of the run was also in the end zone.

Why would B decline such a penalty? An illegal pass carries a loss of down anyway. In this case, if the penalty was accepted would you enforce the 5 yard penalty from the suceeding spot (since this was a loose ball play) that is the 20 yd line and have A kick from the 15?

Maybe I'm reading too deep into this, but I would like input from others............Thanks