Heart attack would have woken him up. When somebody dies in their sleep with no previous complaints it is almost always cardiac arrhythmia. In such a case the cause would be recent heart surgery (which Scalia did not have) or exposure to arrhythmia-inducing chemicals.
IOW, poisoning is a reasonable guess at what killed him, given his serene appearance when found, the absence of any complaints before or after he went to bed, and the absence of recent heart surgery which is the “natural” cause for cardiac arrhythmia in such a case.
And don’t you DARE accuse me of ignoring the nefarious things of this regime. If you knew half of what I know about what this regime has done you would go absolutely nuts, because you would never believe it.
Also from the Washington Post article above.
https://www.washingtonpost.com/news/post-nation/wp/2016/02/15/conspiracy-theories-swirl-around-the-death-of-antonin-scalia/
“You have a Supreme Court Justice who died, not in attendance of a physician,” he wrote. âYou have a non-homicide trained US Marshal tell the justice of peace that no foul play was observed. You have a justice of the peace pronounce death while not being on the scene and without any medical training opining that the justice died of a heart attack. What medical proof exists of a myocardial Infarction? Why not a cerebral hemorrhage?”