you can also jam transmissions. You can also hide in the debris fields. The republic could very well be sending scouting parties through the debris fields to make sure nothing leaves, your blockade, board one and fly back... mm, quite fun. It could be interesting, the shuttle could feign as debris, or it could be investigated by those just far too curious, or Traya could be aboard and manipulate the crew's minds.
And if the ships are not close enough to the debris field, then they are not scanning and Beni's scenario plays out.
It is a lot harder to hide a capital starship in a debris field than a ship the size of the Ebon Hawk or the Millenium Falcon.
Also, if everyone would look at what all Revan accomplished in KotOR I, taking on Malek on the Star Forge, despite all of Malek's advantages he still ended up getting killed by Revan (whom still was missing a lot of his memory).
Kreia acknowledged Revan was probably way more powerful than she was.
Kreia may have been a master at deception and duplicity, however Revan was also a master at deception and duplicity, if you listen to HK-47's explanation as to the differences between Revan and Malek, it is fairly obvious that Kreia and Revan are probably evenly matched when it comes to deception.
Additionally her Sith Assassins weren't the only ones with Stealth Field Generators, heck in KotOR, if you are a scoundrel starting off, you get a stealth field generator. They aren't exactly rare, and the mandalorians were using stealth generators quite a bit, so Revan's troops probably knew how to deal with stealth enemies.