It would be easier to compete with them, they would lose their role as being the gate keeper of acceptable debate on a huge part of the internet, so there's a huge down scepticism from my part, thinking "they will find some way to taint and contaminate this whole project... somehow". Twitter would never actually embrace this idea, certainly voluntarily.
Like, at the minimum they can stand up a WordPress blog and use a plugin to do so from their own domain. I'm not holding my breath in the meantime.