Re Posie, I imagine it's less about actively wanting to be arrested, (who wants that?) and more about thinking on her feet in terms of publicity. Either for the cause she went there to talk about or, subsequently, the way that these talks are dealt with by the police.
Police have stood by whilst women have been intimidated, police have ordered lesbians off chairs, police have mounted their horses to disperse women handing out leaflets.
There are two strands to this debate. Firstly the actual issue, and secondly the way women taking about the issue are shutdown.
Posey quite clearly makes snap decisions all the time when confronted with the unpredictable.
And this is what she did.
She wasn't going to allow the illegal prevention of her talking about this issue. And she was going to let the world see it.
It's not difficult to understand.