Prem,
Appreciate the nomination, but discussing this on this list doesn't really have a lot of upside. If any candidate is suggested, and the suggestion isn't immediately followed, then it just ends up shining a negative light on the candidate. That's not in anyone's interest. There can be all sorts of reasons for why even just the timing isn't right.
On the particulars, Sean has done great work for Rails. We're all better off for his contributions!
The core group will take the nomination under consideration, but for future reference, please ping any Rails core member if you wish to nudge or suggest a new member. Thanks!