As the joke goes a gun is better than a camera:
I don’t know enough about moose to known if it was sick or just mad with the rut. I do know that just about all my relatives in Northern Maine have moose attack stories. You don’t hear many stories of people actually getting killed, but they’re HUGE so it doesn’t take much.
Carry your damn guns, they aren’t just for two-legged predators. Also if there are BIG dangerous animals in your area you might want to consider what the gun you’re carrying might do if you get attacked by a REALLY big critter.
Some talk on dangerous game carry guns here.