If there was no update/patch, I might side with Epic, but as soon as the fix was out and everyone needed to update, users needed to know the risks of inaction would inhibit. Not least of all because people may start reverse engineering the patch.
Epic has decided this is revenge for them not using Google Play, but if you look at Google's bug efforts historically, this has always been how they handled these issues. They've been highly consistent about it.
If Epic wants to keep serious security bugs under wraps in the future, maybe they shouldn't rely on unpaid third parties to audit their code.
PS - Google gave them 7 days from patch release, so most auto-updaters likely updated the installer.