Sort:  

not exploitation if by design
what part in developing did @ben have?
he was one of the first and got one of the largest payouts and has an account called @imadev but no github

Exploited if by incompetence of design.

I have no clue who that is or if he had any role. He clearly knew enough to code up a script for this so this was someone who knew the chain, knew there was a loophole or was testing, and knew how to write a few lines of python. You can do an investigation into who fits that character profile better than I can.

ben = Ben johnson secret director of steemit inc

https://www.corporationwiki.com/p/2zgw0l/ben-johnson

going by github steem users and early knowledge of underlying workings i would guess revflash

Coin Marketplace

STEEM 0.19
TRX 0.14
JST 0.030
BTC 59908.77
ETH 3191.82
USDT 1.00
SBD 2.43