I think they're thinking of locking in the SP for a set duration, kind of like a CD at the bank.  That's the way I conceptualize it.  So if you locked in for 13 weeks, you'd have to wait for those 13 weeks to pass before you'd be able to power it down and cash out.

The only wild card would be how we handle new SP rewards (curation, author, and the like) Perhaps the 4 week turnaround time might for those might not be a bad idea...