Excuse my ignorance, but who is this and why is it interesting that he's working for Etsy?
He was active in the Ruby community.
The company he co-founded was acquired by Twitter. Then he worked in Tumblr ...
So in a nutshell he is well known in the startup world. Or at least this is my impression.. .
It might help to put in the link Avi Bryant, Creator of Seaside, joining Etsy.