I’ll tell them you said I could.
Why don’t they just buy used luggage, then plant the luggage for the dog to find?
Why involve a third party, especially one that hasn’t consented? (Unless there is something in the fine print I can’t read.)
You can probably get a bunch of used bags cheap, and make sure that the dogs don’t get too familiar with any particular one.
I would also resommend that the baggies they use are properly colored and labeled as being the property of the appropriate law enforcement agency, so that if a baggie gets lost and turns up in a customs inspection, no one gets in trouble because Fido has a stuffed up nose.
And the downside is . . . ?
One of them isn’t.
Please read thread before inserting foot into mouth.
Link was blocked for me. Thanks for the quote, sir. 
That apparently was the concern, that the dog would be too familiar with their training bag. The Japanese media has been pounding question to why that could happen without consent.
I wouldn’t be surprised if there were something in the ticket about that, yeah.