I believe this code is importing immutable blocks only.

https://steemd.com/

looks like it takes 15 blocks deep to become permanent.
i assume they are coming in 45 sec late.

https://jnordberg.github.io/dsteem/classes/blockchain.html#getoperationsstream

https://jnordberg.github.io/dsteem/interfaces/blockchainstreamoptions.html#mode

Streaming mode, if set to Latest may include blocks that are not applied to the final chain. Defaults to Irreversible.