I also noticed that they inserted rule 2.1 into their Terms of Service (Russian translation) today. This particular item wasn't there yesterday.
Have you considered bringing your case to their licensor and filing a formal complaint? Also, since it seems like you're in the right here, why not explore third-party mediation? In my experience, the following are reputable mediators:
https://thepogg.com/https://www.casinomeister.com/https://casino.guru/https://www.askgamblers.com/Even if they choose not to respond to any of the mediators listed above, it could still negatively impact their reputation on those platforms.
ps. I edited your quote to show the screenshots.