It wasn't explicitly announced to the users to stop or suspend trading.
Yesterday's announcement says:
>Steem-Engine will no longer allow trading of the old LEO token that lives on the Steem blockchain.

Unfortunately, it didn't go this way.

It was only in this post that it was stated clearly as:
>any tokens purchased now (since the snapshot is over) will not be reflected in your airdropped balance on hive-engine. Please change your activities accordingly.

Anyway, I ain't as smart as you guys. I did notice that you cancelled all your buy orders but unfortunately, I couldn't figure out why. 
Some people are still putting new buy orders.