I'm not sure - it might be worth exploring - for example the account is initially set up so you can view all the settings and things and pages but you can't actually post or vote until you set everything up. If you don't do so within a certain set period then the account is deleted.

I think the problem with this would be the blockchain basis where you can't really delete things, however there are likely to be ways round it, - provisional accounts could be cached on an external server (like images) until they are fully activated.