They allow multiple accounts. This is a fact and it is easy to find in their terms and faq.
You are right.
They also have this written in their terms and faq page:
We may terminate or suspend Your Account immediately, without prior notice or liability, for any reason whatsoever, including without limitation if You breach these Terms and Conditions.
Upon termination, Your right to use the Service will cease immediately. If You wish to terminate Your Account, You may simply discontinue using the Service.
https://rollbit.com/terms-and-conditionsWe reserve the right to disable accounts that have been created with the intention to abuse our bonus, coupon and chat features. Creating new accounts to circumvent our Sportsbook limits is considered abuse. Please do not do this!
https://rollbit.com/faqYou created another account to circumvent limit you made on their casino.
I can interpret they have the full right to disable your account because you tried to circumvent previous deal you made with them for self-exclusion.

You can't expect to get rid of addiction, gamble in the same time, and expect casinos to play games with you.