They had him DL and install Logmein Rescue (LMI Rescue) which apparently scanned his system (Luckily he doesn't keep any financial stuff on his computer, so that should be safe). Rather than call me, he called the number for help.
The message would not go away and long story short, he panicked.
My son went on his MBP to check his work schedule using Google chrome and got a large blue message that it was infected with a virus and to contact support.