Welcome. Never heard of Golden Throat nor a Guild truss rod cover that had a date range nor one that used that font. The shape seems wrong either because a Guild TRC was trimmed or it was not a Guild TRC.
So if I had to guess, and that is all I am doing - guessing - I would say that a previous owner had a custom truss rod cover made and engraved to commemorate something that was important to them but is now obscure to us.
Since "golden throat" often refers to someone with an exceptional singing voice I'm going to say it was commissioned to honor a bandmate who died too young.