(This is necessary if we haven't killed Flow's Occupation Controller. If we fix T76778, then we only have to consider security issues.)
As Hostbot, when I create a new Flow topic on Wikipedia_talk:Co-op/UserName using the Flow API,
then so long as that page does not exist,
that action should birth a Flow board.
Rough sketch: Flow should check the user's rights, and if it has right flow-create-board (granted to new flow-bot group), then Flow should ensure Flow on that page, using some variant of ensureFlowRevision