Like all combat recons, it’s meant to hide in FW ‘plexes, either solo or in a gang, as a support ship that can lay down a bit of damage as well.
There are a few non-ECM fits that field a decent shield tank, but on its own it still doesn’t excel in any way over other choices.
If you’re flying a Rook, you’re flying it in scenarios where the D-scan immunity improves your engageability but for which the element of surprise is not absolutely crucial to your victory. Hence the FW ‘plex, where they only see you when its too late (as they’re warping in to what they though was an empty site).
Not every ship in the game is designed to be viable in both fleet and solo scenarios. The Rook is a fleet support ship for when your fleet needs more mobility than a Scorpion can handle, doesn’t need a covert cyno, and could benefit from some extra damage.