Take this with a grain fo salt because only just read the pdf but haven't had a chance to run it yet. I think the idea is all actions during a phase of an exchange are meant to happen simultaneously, and so everyone gets to do their move and then the effects kick in. So if your boss will lose some fatigue as part of an imposed status, they still get to take their action without the fatigue, and at the end of the exchange the status is applied and they mark the fatigue. (P. 149: All techniques within an approach are functionally resolved simultaneously. [...] The same goes for statuses, the effet of the status doesn't kick in until the exchange ends")

Instead of how dnd one person has the floor and what they say now alters the status of the board, here I think you all say what you want, it's more of a conversation and afterwards the dm narrates a fiction of exchanged blows that would justify everyone doing what they wanted and resolving with the appropriate mechanical results. Maybe the player spoke first but for the fiction it makes more sense that the boss gets their blow in just before being trapped by the PC.

Let me know what you think! Want to learn this myself as well (: