If this is true, kindly post a scan of the TSA letter to this effect - becuase if it's not in writing, it's hope, not policy. 
If you can produce a verifiable policy document to proove your assertion of TSA specifically allowing this self-defense device on plane, I will make a public apology to you. 
In the meanwhile, I have contacted the TSA myself with a  printout of pages with your device seeking a statement to the same effect as your claim. 
I contacted (By mail) Chad Wolf, Assistant Administrator
Office of Transportation Security Policy 
TSA HQ: TSA-9
601 South 12th Street
Arlington, VA 22202-4220
I hope that he can clarify this matter.