I don’t know if I’d say not knowing his whereabouts is the same as him missing. As far as I’m aware the guy doesn’t have to share where he is and especially not to random people on the internet. So I think it’s a little premature to consider him missing instead of just saying he’s avoiding the public eye, which is understandable.
When a person is nowhere to be found he's missing. It doesn't matter if he's hiding or taken away from the public eye. Every missing person is somewhere surrounded by people, who probably doesn't know him or don't want to communicate with the world of the person's location. Literally, to those in search for him, he's missing. The last I checked, "avoid" reflected as a strong synonym for missing. Since he's avoiding the Judge, it's preferable to say he's missing. Additionally, on the hunt for him, the Judge actually went to his house, not on the internet.
Whether he is missing or not, we know that he's a fraud even before the sentencing. Now, he may be avoiding or hiding people because more people are learning the truth about his personality. We don't know his reasonings why he is out of the limelight. But people should be very careful in believing what's out in the cyberspace. Don't screw up your funds for some strangers telling you that they know about an investment you can reap high profits.