Punishment is required.

However, because we want people to come clean of their own agency (both to make crime-solving take up less public resources, and to make it such that criminals don't have to wait to get caught before becoming productive and non-harmful members of society), we should adjust incentives such that the punishment for coming clean of one's own accord is a little less, and the punishment for getting caught for the same crime is a little more.

Maybe it could be implemented as adding an extra punishment for concealing a crime?

I agree, keep in mind this criminal did not come clean on his own accord. There is no indication he would have ever come clean. All we know is that he did non-criminal activities on youtube.

For all we know he could have been operating a human-smuggling operation from his current local.

Either way he knowingly and purposefully avoided prosecution.

I agree. I think we should incentivize more people like this to come clean rather than spending our own resources having to go out and search for them. I think this will result in more people like him getting the punishment they deserve, and also makes it so that we turn more of these people back into contributing members of society.