Per ICAO, the definition of a passenger baggage is personal property of a passenger which are used during his/her trip for comfort and convenience. It includes gifts and souvenirs however does not include merchandise samples.
If he/she is going to wear this stuffed clothing during the trip, DGR 188.8.131.52.1 could apply, however that is very unlikely. Since it is clearly a sample, it does not come under the definition of passenger baggage.
Even if the first carrier allows the carriage, the second carrier may very likely apply the rules and refuse carriage. You will be breaking the ICAO rules and also placing the passenger in an awkward situation. Rules are made to be observed.