No cause of death has yet been given, two months after Moritz's death.
He finished four as-yet-unreleased books before he died, which would seem to indicate he had an illness and knew he was dying.
My own guess is cancer.
That would explain the silence from his family and his own website about the cause of death. Moritz claimed cancer is not a disease, and that the body can get rid of cancer cells on its own and doesn't need medical treatment.
His family may well have wanted him to avoid the well-deserved public shaming (and to a certain degree, ridicule) of Hulda Clark, who became rich with her claims to have the cure to all cancers - and then died of cancer herself