I think I've got this down but I just want to see what everyone else thinks.
Situation:
I've moved and taken a standby token with Vader during his activation. Luke then activates and moves into base contact with Vader with the intent to use his "Charge" ability. As an (pardon the magic phrasing) instant-speed response Vader spends his standby token and beats his son over the head before Luke can make his attack from "Charge".
I.e. If Vader has standby and Luke charges him, Vader can use his standby token to hit Luke before Luke can hit Vader.
I cite this precedent:
QuoteRRG pg 41:
For example, Darth Vader performs a move action to move into range 2 of a unit of Rebel Troopers that have a standby token. Before Vader can trigger relentless to perform an attack with the “Saber Throw” upgrade card, the Rebel Troopers spend their standby token to perform a move, taking them beyond range 2 of Darth Vader. With no enemy unit in range 1–2, Darth Vader can no longer perform an attack.
It's a different action-reaction in utilization of the token, but the "Before X (unit) can trigger Y (ability)" is the same concept. I will also point out that Vader is not compelled to spend his standby token when a unit enters into range 1-2, he may spend it (which means he can hold it in reserve).
What do we think?