The NCAA isn't intended to protect the public, except peripherally. They're intended to make things "fair". State Bars are intended to protect the public. So if a lawyer or a doctor commits a crime that makes their suitability questionable, they're punished by the bar. It's why fraud crimes are so heavily punished by lawyer bars and why DUI are so heavily punished by both organizations (in theory). That's not the purpose of the NCAA, so I don't think they should be involved.
Should the NCAA get involved if coaches cheat on their taxes? What if they are involved in a pyramid scheme? What if they commit insider trading? What if they are involved in an email fraud scheme? I don't think the NCAA should be dealing with any of those things. The reason they got involved at Penn State is because the story was so horrific. I understand that impulse. They have power and they want to use it to help. But I don't think this is their realm and I think they should have left this one alone.