The Russian intelligence services are good for two things:
1) Killing Islamic terrorists.
2) Leaking climate scaremonger email.
If I were these scientists, I’d go out of my way to avoid people with umbrellas and tell waiters, “No polonium in my salad, please.”
Bless Putin if he did this. Now can he do something about the birth certificate.
IIRC the polonium was in the tea, not the salad so it would even harder to prevent another episode in Great Britain.