horses on the roads

https://www.youtube.com/watch?v=kHK6vSnIByc&t=1s

i think i did everything right here. But can anyone tell me, maybe you've got someone who rides, why did they stop completely after a few seconds. I was going to move into the oncoming lane once the traffic had passed, then crawl past anyway. Was it because the bike engine was making the horses nervous so they stopped? or did they stop thinking i would crawl past but staying in the same lane as them?
The interesting thing i did find, on equastrian forums, spelt that wrong i think, is that most bikers are absoutely fine and considerate to horse riders, cyclists are mostly ok too. Its car drivers that go too close, too fast. How odd is that. The ones that also scare and maim cyclists are also the ones who scare horses. Not all drivers of course, but the majority of incidents i find with horse riders wearing action cams, its car drivers freaking horses out.

I wonder why this is. It has to be mentality surely, the same reasoning these people who only ever drive, they become completely disconected from the outside world. Whereas a cyclist, biker, who drives, is more in tune with whats going on and how to drive nearer to vulnerable road users.