Simply, when an event like this happens, it’s basically inevitable that someone is going to pop out of the woodwork and end up bombing the shuttle with a full PDA of TC. It’s not particularly healthy for the game in my opinion.
I don’t know how to code a change for it, but I’d suggest either ignoring the sleeper agent event if it rolls if evac is irreversably coming to the station, or have it reroll for a different event type.