It means when you have an attack dog don't be surprised when it bites - e.g. antivirus applications are looking for virus signatures, so when 3rd party applications that don't encrypt their virus signatures used for detection, then the resident antivirus is likely to detect and alert on the unencrypted signatures.
That is after all what you want your antivirus to do.
Yes it is safe, but as the other link suggest you should remove this toolbar, etc. and save yourself the grief.