Is there anything in the arbitration clauses forbidding them from cancelling your account if you invoke arbitration (regardless of whether you prevail or fail?).
At the individual dispute level but in the long run arbitration means you don't lose your risk level which will almost always cost you a lot more than whatever the actual arbitration/credit disputes cost.
I suspect (but may be wrong, I don't know how trigger-happy the risk level changes are) the absolute number of events needed to trigger a risk level loss at the scale of Twilio would also represent a catastrophic number of arbitration cases.