I can't speak for this event but similar ones are held across northern England throughout the year. In my experience of "keeping an eye on them" I have always found the riders to be extremely courteous. They are given a pre-ride briefing by the organisers during which they are told they must always give priority to walkers and cyclists. They must also stay on legal roads and byways that are open to vehicular traffic.
I have, on several occasions, commended the organisers on the behaviour of the participants.
The main problem is the noise that they generate, but, in my opinion, the hills and dales are open for everyone to enjoy as they wish LEGALLY. And, if they are on a legal route I have no problems with them.
Slightly off the point, but on a national car rally one participant started blowing his horn and flashing his lights at me as I was driving up the hill north from Askrigg. This was not a timed section but a road between stages so they should obey the rules of the road. I pulled up so as to block his passage and got out wearing my uniform! He was extremely apologetic when I threatened to report his behaviour. I mellowed at the end and didn't.