Since the 1500 lbs in that article is a round figure, I suspect that is an estimated live weight, not actually weighed, since weighing a moose before field dressing is pretty difficult. From what I have researched, which is supposedly based on NB road kills, a field dressed moose that weighs 950 to 1000 lbs would likely go about 1500 lbs live weight, more or less. As with the 2 bulls my sons tagged, the one with the significantly bigger antlers actually weighed less, so antler size is not always a final indicator of weight.
I don't think you'd find many moose over 1500 to 1600 lbs live weight in NB, maybe some in the Yukon or Alaska. I grew up on a farm where we raised 100 or so beef cattle every year. When a steer weighs a ton live weight, which we used to get Holstein steers to that weight often, they look pretty big, bigger than any moose I've seen.