[AdelaideSimone]

Contract law is rather a mess, but, IIRC, one the main, generic exceptions to contract clause enforcement is if is illegal, unconscionable, or violates public policy.

Many states have codified tort laws as being in the interest of public policy (e.g. most consumer protection acts). If this person were to sue under such a statute, it allows courts discretion in nullifying clauses like this arbitration clause.