Good ingredients vs bad ingredients

It is most likely their own spice mix, or their own recipe they've contracted to have made by a local processor.

Silicone dioxide is a naturally occurring substance that is regarded as safe by the FDA from what I've read. 

MSG is a flavor enhancer associated with the flavor of umami.  It is controversial, but is generally considered safe as a food additive.  People can be sensitive to it.  My mom avoided it like the plague, saying it caused her all kinds of problems.  Personally, I've never noticed any issues.  MSG makes for interesting reading. 

Do I use it?  No.  Do I avoid products with MSG?  Generally, yes, but only because of some of the things I've read about how the food industry uses MSG to create cravings for their products.