Caseplay on fouls correct?

[tskill]

NFHS rules, wondering if anyone could explain the caseplay that is in the referee magazine naso edition page N15 entitled "Each Team Fouls" wondering if this is correct? The play is:

Play:
Team A's ball, first and 10 at its own 20. A1's legal forward pass is intercepted by B2 at the 50. During B2's advance, B3 blocks A4 in the back at team A's 40 yardline. In the process of making the tackle at team A's 30 yardline, A5 grasps but does not twist B2's facemask. How are the penalties enforced?

Their Ruling:
Team B can keep the ball because it gained possession with 'clean hands' but both penalties will likely be enforced. The 10yrd penalty for B3's block in the back is enforced from the spot of the foul - moves ball to the 50. Then 5yrd facemask by A5 is enforced leaving team B with 1st and 10 from the A 45.

Is this correct? I thought that if you read NFHS 10.2.2 in order for B to retain the ball (since they got it with clean hands), they have to decline it's opponent's foul.

Here in this caseplay they are saying that both fouls are getting enforced, is that correct for NFHS?? and what rule reference?