I am pretty sure China and Hong Kong both have similar RICO laws, most civilized countries do.
RICO laws are often used to prosecute criminal organizations that play jurisdictional loopholes.
Conspiracy to commit a crime is a crime in and of itself.
Since I am not familiar with details of Chinese jurisdictional laws, I'll give you a similar case law under US laws (as I'm sure the judicial theory and principles are similarly applicable under Chinese laws) -
Marijuana is legal in the State of Colorado, but it is illegal in the neighboring state of Kansas. If a person legally purchases marijuana in Colorado, and knowingly gives it to another person who transports it to Kansas, the original purchaser is also committing a crime, even though the initial purchase in Colorado is legal. It's called a conspiracy to commit a crime. And since it involves more than one person, RICO statutes can be applied.
In this case, the crime under conspiracy is smuggling. Even though airsoft is legal in Hong Kong, the organization's intent is to smuggle it across the border into China by deceiving Chinese Customs. Therefore, everyone in that organization is guilty of conspiracy. Everyone is prosecutable under RICO principle.
Just FYI -
You just described textbook RICO violation.
The fact the airsoft is legal in Hong Kong is immaterial.
The fact that buying airsoft is legal in Hong Kong is immaterial.
The crime is conspiracy to commit smuggling.
Smuggling means intentional deceiving Customs to avoid Customs inspection. It has nothing to do with what the actual goods are. Deceiving customs = smuggling.
And since this involves more than 1 person, it qualifies as a criminal organization.
Therefore, RICO violation exists.
Under RICO, every person involved in the organization is prosecutable.
Defense attorney is doing his best trying to defend his client, so he looks for any loophole he can find. Most loopholes don't work. If you think this is a valid and workable defense, why don't you go to China and testify on his behalf? If they arrest you, you can use this very same defense.