By sending Steem between two accounts, he inflates transaction volume.  People like coins with a lot of transactions, since it suggests there is a very active community who actually use them, not just hoard them.  I think there's no fee to send coins with Steem, so it costs him nothing to "juke the stats".

@davman - So basically he is posting huge orders for 1 minute so the liquidity rewards apply.  Then he buys his offer or sells his bid.  The Steem system registers this as a legitimate transaction but it is not (unless this was by design?). 

You can see how @adm and @alittle are at the top of the reward queue constantly.   https://steemd.com/tools

A simple fix would be to not allow someone to trade against themselves.  In every market around the world, this is a rule.  I have been a professional trader for 10+ years.