Prevent orpahned participation error

See: https://www.pivotaltracker.com/story/show/84640002

- [x] ask yourself: is this PR complicated enough that you should write
      integration tests?
- [x] ask yourself: do you feel that things are well abstracted?
- [x] do a self code review (read through `git diff` or the github UI)
- [x] complete all relevant todos in your code
- [x] self QA (make sure the app still works, along with your change)
- [x] get review from a team-member with knowledge of this codebase area
- [x] **team-member said ship it! (:ship: it)**
- [ ] self QA on staging
- [ ] do any changes need to be made to prod before a deploy? List them in
      the `deployer checklist`
- [ ] the tests are passing for this branch on semaphore
- [ ] merge! Celebrate your success!