'Battle Rattle' generally weighs more than that. About 30 pounds for the base armor, 12 pounds for the SAPI plates. 8 pounds for your rifle puts you at 50 before adding up ammunition, helmet, water, specialty gear (NVGs, binoculars, etc.), boots, grenades, etc.
And like I said already, the Medium Machine Gun mentioned wouldn't weigh nearly as much. 20-30 pounds for the weapon itself, which a normal person can fire standing (albeit not all that accurately). The ammunition weighs less than a quarter of your previous math (comes to around 400 rounds per 10 kilograms). Now a troll has it, along with a Gyro-Mount for recoil compensation.
So yeah, a troll can totally do what the guy is thinking, although the riot-shield built-in to provide armor would be unwieldy. They can do it with about a third of the carry-weight assigned by the book, assuming 12 Strength.