Yes, it's hard to guess a bears weight. Their fur is thick and most people see so few, even fewer that are actually put on a scale.
I've seen quite a few bears here in Pa, a place that's known for 600+ pound brutes.The old timers used to talk about dog bears and hog bears. Dogs had longer legs while the hog bears were stout and fat. But I wonder if it was more the time of year when seen as they do put on the weight in the fall.
The OPs bear is too slim in the body to be anywhere close to 500#. Plus his legs are too lanky. I'd wag 250 - 300 # but it's just that, a WAG. Still be quite a load to drag out of the woods
Now...if he'd be so nice as to step up on a bath scale, maybe we can get a handle on his size.

He is a nice one. Thanks for the pics!
John