Had a situation where a player played two copies of this card and the question was does its ability stack. Player only had a shield trooper without rules text so it became 2 slash. Next black bolt played now does that trooper double to 4 slash or only get 1 more to 3?
The wording of Silence is Golden is
Choose a card you played this turn with no rules text. You get its Recruit and Attack again.
Additionally, it is 0+ Recruit and 4+ Attack. That means the first play of it would be a 5 Attack, 0 Recruit. If no other card was played between both iterations of the card, the second card would be exactly the same because the Card Text on Silence is Golden automatically disqualifies it from applying. In the scenario you presented, only the S.H.I.E.L.D. Trooper would apply.