if ever there was a incentive not to use a route..

There is some twaddle here. Its a simple note. There is a bull there. If you are scared of bulls go somewhere else. Easy.
In no way confrontational or anything. If anything its a courtesy to let you know rather than find out in advance.
As for the language, that’s a traditional phrase.
I know that nowadays it should be more gender neutral but maybe that’s a bit pc for some.
Molegrips. The farmer doesn’t have to say anything at all.
Beef bulls are dozy things. Heifers can be pushy but a good slap sorts that. Yes people have been killed but not as many as those falling down the stairs. Shall we have notices on the steps in town?

Countryside not coming with an instruction book shocker

Give it a rest, I was out in the countryside all day when you were in nappies. I’ve never demanded signs in the countryside in my life. The point is that he has gone to the trouble of putting up a sign that tells us nothing. Why? What’s the point? I can see a sodding great bull thanks, didn’t really need a sign for that. So what was he trying to say? Is it a particularly dangerous one? If so, why not say that?

restricting access to a PROW is the issue with the sign even if the restriction is implicit rather than explicit

however if the PROW user has a dog there is a fundamental problem with cattle which has led to the death of a small number of people

as usual there are shades of grey but IMHO the sign is unnecessary, if it is necessary the livestock shouldn’t be in the field, and people with dogs should have a plan or avoid livestock and take alternative routes the PROW user not the dog has the right of access, the dog is there accompanying the user