It's strange. What are his options?
1. Keep holding onto whatever he knows, knowing it makes him look suspect?
2. The police possibly decide to offer him immunity down the road just for closure's sake.
3. He could tell what he knows publicly. I.e. maybe "Yes, he's alive, but there's a reason I can't tell you where he is." That would be a start, but then everyone would just press him for his location. I'm assuming if he was alive, only a really good reason could cause Clint to hold onto the secret for so long.
4. He can't very well publicly he admit he contributed to his death because that would land him in jail. And if he knows something, his own safety could depend on his ability to keep his mouth shut.
I wonder how often people reach out to Clint and ask him to share what he knows. I bet several times a year.
I've also even wondered a couple times if they've checked his brother or Clint's phone/email records to see if Brian might occasionally reach out to them? That they somehow do have more information, now, but are protecting him from public scrutiny? Seems far fetched, and probably just a sad hope as I'm sure relatives WISH he HAD contacted them and he hasn't. But it's crossed my mind.