It makes it to the top backorder list because the namejet people identified it as being a possible name people will fight over if enough people know about it. (the whole purpose of the list)
I agree with this also, but pre-release names are often pulled before you can place a backorder when using this tactic.
That just happened to me again today with several names.
I had names in backorder at SnapNames and I was the only bidder and tt went into public auction. There was another domain that was about to expire and they pushed the drop date in june and they pushed it to august. They're doing it because they know they can and no one is there to stop them.