Something is escaping me, I don't see why it isn't a safety (or tack-on) with 2014 rulebook wording. Team B already had the chance to decide which option is better for them.
10-2-2-b Fouls by the offensive team behind the neutral zone. For the following
fouls committed by the offensive team behind the neutral zone, the penalty
is enforced at the previous spot: illegal use of hands, holding, illegal block
and personal fouls (Exception: If the foul occurs in Team A’s end zone the
penalty is a safety.). However, see Rule 6-3-13 for offensive team fouls
during scrimmage kick plays.
Team B can always choose enforcement at previous spot. Even if the subsequent ball doesn't belong to B, it's still a safety with 2014 rulebook.
I'm missing something but don't know what.