Similar request: T263934. Though if patchdemo just uses default config vars from extension.json for a given extension, those likely need to be changed/added before StopForumSpam could be included. See also: T272059 - completed.
Pull request created: https://github.com/MatmaRex/patchdemo/pull/241
Stalled on wmfcloud memory issue (see pull request).
PR merged, resolving for now.