Take a closer look guys. The mounting points for the bolts are rusted away, gone. That's why it came off.
You gonna have to have it spot welded back on. However, those spot welds are probably going to rust and your cat shield is going to fall off again.
Yeah, the cat might rust a lil faster without the heat shield, but that thing has some thick metal in order to deal with the high temps it reaches. Also, there is another heat shield in the same location that is under the "tranny tunnel" or console area.
personally, id leave it off.