It's the team behind the STEEM engine curation train, and they have posting authority because they run/ran a vote exchange on their website.. They don't want to be steem-engine and it's obviuos once you discover who they are - that they are different from steem-engine..

But somebody posted about how their website was down and thought the @steemengineteam hacked steem-engine lol - but I replied to them thinking they were mistaking steemengine.net for the steem-engine exchange - and I knew of the curation team long ago - it's so easy to misunderstand when someone else has a confusing context too!