Just like in 1st Edition, the rules on tractor tokens specify that they only cause the defender to roll 1 fewer green die "During the Engagement Phase". Attacks that occur in other phases, such as the one from the soon-to-be-reprinted Snap Shot, gain no benefit versus targets with tractor tokens (unless/until FFG changes this unintuitive rule via FAQ).

Never mind. The rules changed.

That is a big ouch to remember.