Quite.
There may be no good reason to, but the choice should be there to make. I think you may have unintentionally highlighted my point about equal footing. A lot of Humanist ideology is about making people be critical of their beliefs, it is about questioning what many people take for granted as 'right'. In this respect, why can't we have a poster on a bus? It's not a question of forcing Atheism at people, it's trying to get people be rational. Perhaps the reason we need to advertise Atheism - perhaps that's the wrong word - is to educate the general public about what it means to be secular.
Yes, the view of atheism is probably exacerbated by a few outspoken individuals. But that is just as bad as saying that all priests are paedophiles or that all Muslims practice terrorism in their spare time. Clearly intelligent people will make the link that not every Muslim is a member of Al-Qaeda and that not all Atheists leave poo on the vicar's doorstep.
I don't mean in a "watch your back" sense - though notably in the US "admitting" (I use the word with a lot of distaste) you're an atheist basically hinders your chances of ever gaining political power. My point was directly aimed at the Pope, the Catholic church tolerates (more or less) other religions and yet Atheism is shunned and publicly decried?
Forcing people to change their minds is always a losing battle, so no, I wouldn't expect people to - I just foolishly expected the leader of one of the world's largest religions to exercise a little restraint in a country that is extremely secular (apologies if I got this wrong in a previous post, I just looked up the figures, approximately 62% are atheist/agnostic).