STRUCTURAL MEMBER or Gravel Guard?

[jdstrickland]

I have a mechanic that is trying to tell me that the large steel plate with the words DO NOT OPERATE UNLESS THIS PLATE IS IN PLACE (or similar) stamped on it is just a gravel guard. I had the Oil Filter Housing Gasket replaced and I am noticing a lot more (A LOT) creaking coming from the front of the car, especially after using the brakes -- I brake to a stop, then when I proceed I can hear the front end shifting around. I think he may not have sufficiently tightened the bolts, which is entirely possible IF his view is that the plate only needs to not fall off. I completely get the gravel guard thing, but if a gravel guard then why stamp big letters warning people to not drive without it, we drove cars for 100 years without a gravel guard, they are not imperative. They are nice to have, but they are not imperative.

What do you think, structural or just aerodynamic and/or gravel protection? My vote is, structural.