Right outrage, wrong response
I can relate to Boyce's outrage at learning of US string-pulling among those we call our allies. I'm not sure what he might have thought selling US secrets to the Soviets would do that would help in any way, though.
This is supposed to take place in the early 1970s, not too long after The Pentagon Papers and Watergate. Idealistic short-sightedness is one thing, but even so, it shouldn't be too tough to see that the best way to change the situation would be to pass on documents - but to the press, not the Soviets.
All those printouts he got & shredded could easily have made their way to the press. Or, if he was concerned about getting busted, he could do a Deep Throat, gather info and try pointing reporters in the right direction.
I never really saw any compelling reason for him to go the route that he did.