Actually, IIRC the bar is NOT a slide rail for the front seat. The seat slides on 2 tracks which are bolted with 4 bolts to the floor. The black bar is a slide rail for the seat belt buckle. The buckle is mounted to the seat with a couple bolts. The bar runs through the actual buckle mount and is responsible for keeping the buckle "upright" as the seat slides back and forth over it. Try removing the bar altogether and you'll see what I mean - the seat belt buckle will "flop" all over the place.
AFAIK, the bar doesn't appear to be structurally integral to the proper operation of the seatbelt; as I said, the buckle itself is mounted to the seat and not to the bar. In fact, I believe the front of the bar only slides into the center console in some way; it is not bolted in. Only the back of the bar is bolted in.
In my experience, the bar usually bends when it is not clean and lubricated, for instance spilling coke onto it can cause it to get sticky. Then when you adjust the seat backwards, the buckle mount "binds" on the bar and the force of the motorized seat bends it. Or, sometimes it bends when the seat is removed and reinstalled; the bar and buckle mount have to be installed perfectly or the binding occurs, which again results in a bent bar (ask me how I know).
If I were you, I would replace the bar. Forget about straightening it - I've tried that, and it doesn't work. The bar should be cheap at a junk yard. To replace, just slide the seat all the way forward, unbolt the rear of the bar, and slide it out backwards. Reinstallation is the reverse. Make sure to clean the new bar very well before installing it.