Uh, why would anyone bother?
Roger Stone has a reputation as a political operative. My guess (firing by Trump) is he went too far in some psyops and Trump refuses to associate with that.
Everyone knows that polonium poisoning is associated with Russians (Russians deny this, of course). Smells like psyops to me, as I assume that polonium is absent or too small a dose to kill. If Stone goes to the FBI after 20 January, I would find it interesting.