This is what is posted on their site as of now, seems pretty simple, maybe the gunsmith was talking about restricted/prohibs ?
Canada:
Please contact the Canadian Firearms Program at
https://www.rcmp-grc.gc.ca/en/firearms or by calling 1-800-731-4000 to determine whether it is permissible to ship your firearms.
When it is determined permissible to ship firearms, they must be shipped as follows:
Customer Type
Service To Be Used
Consumer
Regular Parcel with Signature option.
Due to changes to our delivery processes for COVID-19, all firearms must be shipped by Regular or Expedited Parcel and include the Proof of Age option. Consumers have to open a Solutions for Small Business account and create labels for shipping firearms using the online shipping tool, Snap Ship.
Contract customer
Expedited Parcel with the Proof of Age (18 or 19) option using EST. Visit Section Mail addressed to children of Policies for an age of majority by province or territory listing.
Customers who wish to ship firearms must:
unload the firearms - there cannot be any ammunition in the firearm or in the package (bullets, cartridges and other ammunition are dangerous goods)
attach a secure locking device to the firearms
lock the firearms in a sturdy, non-transparent container, and
remove the bolt or bolt carrier from any automatic firearms (if removable).
Firearms cannot be shipped via air and cannot have any markings on the outside of the packaging. The customer is solely responsible for meeting all Canadian Firearms Centre regulations