An interesting scenario

[ElvisLives]

How about this one:

2/5, A-40, 4:00 (1), A=0, B=7.
B80 intercepts a legal forward pass, and returns to the A-30, where he fumbles. A88 recovers the ball, and, as he legally advances, A75 blocks B55 below the waist at the A-35. B99 lowers his head and forcibly contacts A88 with the crown of his helmet, knocking A88 to the ground, with the ball becoming dead at the 50.

Ruling:

[Legacy Zebra]

Team A will more than likely elect to offset the fouls and replay 2nd and 5 at the A-40. However, because they did not foul until after last gaining possession, they do have the option of declining offsetting fouls. That would mean enforcing their illegal bloc below the waist from the A-35 to the A-20 and make it 1st and 10. Either way, B99 is disqualified, the play clock is 25, and the game clock starts on the RFP.

[ElvisLives]

Yeah, at first blush, declining the distance penalty for the Team B targeting foul to get a first down might seem to be the most likely option. But, after consideration, Team A would probably be better off to accept true offsetting fouls, and repeat 2nd down with just 5-yards to gain, and much better field position.
Just a reminder that this is not an obvious choice, and we must make sure the HC understands the options, and him make the choice.
And, as you say, either way, B99 gets to watch the rest of the game.
Like I always say, if this happens, get video!🙂