You do understand that the Gates of the Japanese Embassy and the US Embassy are not one and the same?
I understand that you are trying to make some omniscient observation about the great and omnipotent power of the CCP and somehow reduce all Chinese to mere party puppets.
That's in fact horsesh!t.
These people were protesting the Japs because they hate the Japs. They spilled over and found some American proxies to harass, most likely because as we've seen, American diplomatic security sucks right now.
If the Chicoms want to send a message they'll knock on the front door.
Get this straight: The CCP is only powerful as long as they can align their agenda to take advantage of the Chinese people's motivations.
The Chinese people are not and never have been puppets any more than an elephant or a bronco is a directly controlled puppet of its current rider.