Actually, we would only want to do that in the case where the ticket exists in the registry but is expired. If the the ticket is not found in the registry, there would be no metadata available to drive the SLO process. If we want to pursue this course, we would need the check to emit 4 states:

1. notFoundInRequest - transition to gateway check
2. notFoundInRegistry - transition to action that deletes cookies
3. expired - transition to logout flow (as subflow)
4. valid - transition to service check

I was hoping to do everything in one action, but I can see we reduce duplication and possibly provide better behavior with the above.