A few weeks ago I ran http://sto.gamepedia.com/Mission:_The_Temporal_Front again, to get the shield and the weapon.
(I wanted to combine the 2pc set bonus with the 2pc set bonus from the Romulan Navy Set).
When I finished the mission I surprised to find 2 set weapons as possible rewards instead of just the one listed on the wiki:
Next to the Minigun there was also an Assault gun. I took that one, and it was still considered as part of the set,
granting the set bonus.
I'm at work right now, so I can't give any details, but I will check that later when I'm home.