Ok it's not fans but it is an issue for the Hull clubs. If enough of this happens fans will not go, they may not blame the fans of opposing clubs, but if it's not safe then no matter who is causing the trouble the result will be the same. Away fans staying away.
I've been to Hull when the Rugby is not on, but when it has been on, I've not been back since my car was broken into. Every single car was targeted on that occasion as the local crim's knew everyone was inside the stadium. Well if I can't leave my car and now you can't go by coach, then simply you can't go unless you go by train. To be fair I would not have gone today as I was busy. But Hull has dropped of my list of away fixtures to go to even if I do have a free weekend.
Saints had a similar problem some years back at Knowsley Road. There was a local road round the back of Taylor Park near to piggy fletchers, local kids where breaking either into cars or breaking mirrors or doing damage.
I think the clubs response was to inform away fans before the match not to park in that area, as it was an area out of sight off any houses. Also when away fans were parking up there, Saints fans on the way to the match would give them the info not to park there.
If there is a specific place in Hull where these coaches are being bricked. It may not be a police escort that is needed as Hull can't order the police to do so. But they could inform away clubs of this problem and offer a diversion down a different route. I'm not sure where these coaches have been bricked, if it's a main artery that may be impossible to do, but the main road out of Hull is usually pretty free flowing at 40mph so can't imagine that is were they are getting pinged.