Well this is becoming more prevalent by a number of security applications as it speeds up any scan/check as accessing this data is much quicker if the signature data is loaded in memory rather than on the hard drive.
So the rights and wrongs of it those signatures when loaded in memory should be encrypted or not, as they must know there is a possibility that the users resident anti-virus may well detect these signatures. Or is it just the case that, since comodo now only offer the suite version with an AV and feel there shouldn't be anyone who doesn't want their AV (or care).
If the signatures were encrypted in memory they wouldn't/shouldn't be detected, but then there is the overhead of having to decrypt the signatures first, losing some of the benefit of having them in memory.
So in essence it is up to the user, to do as I suggested don't run the memory scan in the custom scan or ignore the expected results if virus signatures loaded by security software are detected.