Hi Fabio,
Thanks for catching it and cleaning it up again.
There are several ways to fight spam in Moin Moin, see
https://moinmo.in/AntiSpamFeatures Blocking an account is not very useful when they are free to create a new one. If anything it's easier to track their edits if they use the same account.
As this appears to be a person actually logging in and being malicious there is very little we can do besides clean up quickly so that they don't get the benefit of traffic to their site. And make it not worth their effort.
Usually some of us will check the RecentChanges page (
http://wiki.ros.org/RecentChanges) and spam is relatively easy to pick out from that. If it becomes more of a problem we can consider more options.
Tully