[shiroiushi]

Depending on who the attacker is, the attack being undetectable might not matter. Russia has assassinated multiple people using polonium, and what was the response? Crickets. They could easily do the same thing to assassinate other people they don't like (along with plane-loads of other passengers), and the only result will be angry words and "condemnation".

[Zanfa]

I doubt those Russian assassinations were ever meant to be undetectable. Rather they were intentional spectacles, where there's no doubt in who was behind it. The goal is to make it obvious, but also deny it officially, while knowing that everybody knows they're lying, just to mock their opponents.

[shiroiushi]

Exactly. I can see them doing the exact same thing with an exploit like this. The point wouldn't be to be undetectable, but rather to be sure the assassination attempt will actually work as intended, and to cause a big spectacle (few things generate news headlines like big airplane crashes).