Missing feature? Moin 1.9.x had configure options to prevent users from changing their name or email:

user_form_disable = ['name', 'aliasname', 'email',] # don't let the user change these, but show them:
user_form_remove = ['aliasname', 'password', 'password2', 'css_url', 'logout', 'create', 'account_sendmail','jid'] # remove completely:

In moin2 aliasname is replaced by name being a list.