Why would team B when trailing ever accept the zap 10 component of any penalty? Since the zap 10 is always a separate and declinable penalty option to the primary penalty enforcement wouldn't they simply decline it? I would offer that this option falls into the "when penalty enforcement option is obvious" category and make sure that we get it right.
Sure, if they're trailing in the 4th quarter I would agree that it's obvious. But what about a tie game? Coach may want to save that time and take a shot or he may want the runoff and let it go to OT. Or in the case of a first half runoff, he may be content to just go to half time whether he's leading, tied, or trailing depending on the circumstances.
For AF Opie's comment, I cannot really think of a good reason B would accept the runoff in this situation. Why wouldn't they want more time on the clock?
If for some reason they did want the runoff, I do not believe it would be applicable. 3-4-4 lists intentional grounding as a foul that includes a runoff if it was thrown "to stop the clock." This cannot be the case because the clock would have stopped anyhow (4th down change of possession).
If Team B were winning and Team A were in desperation mode and got called for IG on 4th down, Team B would want the runoff because they'd be trying to end the game. Plus, if the runoff left the game clock at or under 25 seconds, they wouldn't even have to snap it on 1st down since it's going to start on the RFP. Or, again, if in the first half, they may just want to get to halftime.
If for some reason they did want the runoff, I do not believe it would be applicable. 3-4-4 lists intentional grounding as a foul that includes a runoff if it was thrown "to stop the clock." This cannot be the case because the clock would have stopped anyhow (4th down change of possession).
3-4-4 also lists an incomplete illegal forward pass, which intentional grounding falls under in 7-3-2. Also, the clock stopping anyway for 4th down is immaterial. Team A committed a foul that caused the clock to stop immediately. The rule about a foul being the only reason the clock stops is in 3-4-3 regarding the last two minutes of a half. The only thing that would prevent the runoff for IG would be an offsetting foul as in 3-4-4-e and AR 3-4-4-IV.