>You should always have a plan if your key is compromised. But the point here is that there was no compromise. None at all, the author simply forged the whole

>You should always have a plan if your key is compromised. But the point here is that there was no compromise. None at all, the author simply forged the whole thing and submitted it as part of a legitimate bundle for added plausibility in case there was a human in the loop (which there shouldn't be, and anyway that part could be trivially forged too, just register a bunch of domains over time, get certs for them, then leak the actual legitimate private keys on purpose). So having a primary/backup/backup backup/backup backup backup/backup^n is all useless in this scenario because only the public component was necessary to make a fake sufficient to fool Symantec's incompetent systems.