Polonium is an industrial comodity.
The only industrial use I'm aware of is anti-static brushes used by photographers (example). They contain a minute, sealed quantity of polonium. The alpha radiation ionizes the air, discharging static charges on dust particles, making them easier to remove. Due to polonium's short half-life (138 days), the brushes have to be replaced frequently. And, BTW, the polonium is imported from the low-cost producer, Russia.
Theoretically, you could obtain a lethal dose by buying some brush(es) and grinding up the sealed polonium source(s).
Of course, if you are Russian, you don't need to grind up brushes, but you supposedly like Roger Stone.
Seems like a more likely industrial polonium scenario would be an American lefty who aims to drive a wedge with a false-flag op. E.g., grind up a brush source and use it to assassinate a prominent Democrat in order to blame the shocking crime on the Russians.
As for Roger Stone, it's likely he just wants to be seen as important enough to be assassinated with polonium. IOW, bolonium poisoning. Sickening. But likely the bottom line here.