I'm not sure if you've ever been around a drone but the sound they make is god aweful and impossible to avoid with the amount of RPMs they have to make.
As stated in the article, he used low-noise propellers, and eventually the bears just ignored him. If he's using a modern drone, it probably has a zoom lens on it.
I've filmed a black bear and her cub with my DJI Mavic 2 Zoom, and never really came closer than 60 metres or so away from them. They didn't even notice the drone. I used low-noise props that change the pitch of the sound as well. Here's my video (I'm an amateur!) from a few years ago: https://www.youtube.com/watch?v=iyEPvcLOTUk
However, if you check out https://www.youtube.com/watch?v=9JHyUieKqoU you'll see some video from the author/photographer of these Polar bears. And at one point the bear is heading directly for the drone. I'm sure his curiosity would result in a swatting of the drone if the pilot didn't move back as he approached. I think he's closer than I would dare, but I don't know what equipment he's using.
