That can be easily circumvented with an assistant for a fee. Lots and lots of Russians open accounts in Bali, I know this for sure. A friend of mine opened an account there. It's absolutely not an issue.
On Nut has become an expat ghetto. So many foreigners and especially Russians are living there because it's cheap and convenient. I'm not surprised some unscrupulous police may target foreigners to get some easy money.
Btw, I don't think that running workshops/seminars is actually "working", despite what some clueless people say. It's more like a hobby or meetings of like-minded people. Do you need a work permit to do a hobby?
Only in someone's schizophrenic mind. Look at all those answers in this thread. People are completely detached from reality and live in their own imaginary world - the definition of schizophrenia.