Parents could, but child isn't obligated, which leads to the point it could easily come out.
Beau Bartlett departed on what are by many accounts less than great terms. Cael was recruiting Kurt McHenry when he was in HS. Both have come out with negatives about the program, but neither about cheating or pay offs.
Again, Bartlett less than 18 when he committed and McHenry less than 18 when recruited before committing to Michigan.
Furthermore, NDAs are not valid to conceal an illegal activity. Sure, violating NCAA rules is not illegal, but commission of tax fraud would be (not that I am saying either actually occurred).
Did anyone overhear a conversation NDAs were involved or did Ira say they've been used in this context?