No matter what they say or how they say it, the have to get the website across. Simply write a filter that lookers for those letters in that order no matter what is in between them. This is very easy to do. Then block or ghost that post. You don't have to ban them. In case anyone else for whatever reason types that website, their post will not post, kinda like the language filter. But they won't get banned by accident.
If they try to get around this, they will have to think of a way each time and that takes time. The filter can be adjusted accordingly. It may not stop 100% but it will stop most and take time in between new attempts rather than a new spambot showing up seconds later.
A few other things that may help in terms if restricting social in a way that will not affect legit players much.
Require lvl 10 before you can post in social.
Require email confirmation.
Require chapt one or tutorial completion.
Require people play for a given amount of time and create a channel for new players that they can use until they qualify.