While I personally have nothing against this widget in the UI, had the repo be called e.g. non-production (if you absolutely do not want to call it test), it would do its job. Then a warning at all times: "you are running off non-production repo" would be just fine, including e.g. constant banner on top. In fact it could even be on top of the SUMMARY page.
Now after fresh install, one has to manually change repos away from enterprise to get any updates. That's manual enough process and this widget prominent enough to accept that those who can purchase a subscription, will. Those with ansible deployments etc, will do away with any UI element without a hitch anyways.
(Small note on signalling: RED is usually an ERROR. If one is set on other than enterprise repo, they do not encounter any error, they should be shown e.g. ORANGE warning instead.)