Dark heresy 2 - assassin strike question

[Sinewmire]

I'd say you could use Assassin's Strike after any of the Whirlwind Attack attacks, but by using Assassin's Strike, you are no longer carrying out the action that allows you to make the additional attacks.

If you're doing Assassin Strike, you have stopped doing Whirlwind Attack, you are now making a move at a half-move speed, not making an attack.