If your brother rendered his firearms inoperative then that was his own decision.
I have sent and received dozens of firearms over the years and not once did I send or receive one that was rendered inoperative. You are not even required to have a trigger lock on them.
A direct quote from RCMP website:
Q. Can I send firearms in the mail?
You may ship restricted firearms, non-restricted firearms and prohibited handguns from one Canadian location to another Canadian location if you use the most secure method offered by Canada Post that requires a signature upon delivery. Prohibited firearms, other than prohibited handguns, and firearms being shipped across the Canadian border, must be shipped by an individual or carrier company licensed under the Firearms Act to transport those classes of firearms.
You are required by law to ship firearms unloaded and in a safe and secure manner to deter loss, theft and accidents.
I am curious though about the packaging of the weed...