He may or may not have died from Sudden Death Syndrome, But plenty do and not many, If any would have been in such a stressful environment as he was in. I don't see what Putin would gain from killing him now, He could have done that when he was arrested or at any point since.
People tend to believe what ever suits the narrative of the moment, Take the Palestinian's and all those calling for a two state solution, When Hamas were voted democratically into power, One of there first things they did was to murder all opposition leaders and as many Party members as they could find,
I woul