I think the BBFC have over the years shown themselves to be progressive and wise, especially given their remit, which is to ban stuff like sex and violence, that I quite like.
I heard the original Manhunt was quite good and all that, but the tone is very very disturbing. Not one person who has posted here has suggested that this is suitable for children. It clearly isnt. And I think the BBFC, had they known that this title would not make its way into the hands of tens of thousands of children, through lax parenting, wouldn't have banned it. So I think that while their banning of the title is legally very dubious from a libertarian perspective, they have absolutely nailed it morally. My only concern is that this probably won't hurt Rockstar much, as sales in other countries will be boosted by the controversy