It has to be noted that this applies to US citizens. For EU citizens the arbitration rules do not apply (that at least is how I read the ToS). Instead, they get an EU body that handles disputes:
If you reside in the European Union, you may also be entitled to submit your complaint to the European Commission’s Online Dispute Resolution (ODR) Platform or the Out-of-Court Dispute Settlement (“OCDS”) mechanism under DSA Article 21.
To my knowledge, you don’t need to opt out of anything.