theory:

Tillerson broke rank and undiplomatically yapped about the Russian’s being to blame for the spy poisoning in the UK, even though he was told not to discuss it (probably left in the dark on why however), so he was fired and they killed two birds with one stone and got Pompeo out of the CIA. Who knows about this new woman who is head, or what the plan is there. I will just trust the plan.

Theory: Russian spy poisoning was the latest attempt by bad actors to use a false flag attack to escalate Russian/ROW animosity

Theory: Q, please destroy these people.