Every aspect of what these people have been doing and who they associate with needs to be thoroughly investigated. There is something very wrong with PhD researchers sneaking around with material like this. Especially when they are from China.
By Chinese law every citizen is required to cooperate with and act as an agent of their intelligence service when ordered to do so. What we may be seeing are eager citizens trying to curry favor with the intel crowd by approaching them with, “Hey, I’m important. I smuggled this contraband for our use against the horrible West.”
This need to feel important and involved appears to have been the motive for CIA traitor Aldrich Ames. He was bored with his job at CIA and wanted some intrigue and the feeling of being involved, so he monetized his position at CIA. Suddenly he was important. He was in the center of a huge adventure.
Because of the stupidity of what the various Chinese researchers are doing, I’d guess that’s more the motivation than some plot by Chinese intelligence. But never underestimate the stupidity of a bureaucrat who has zero oversight from above.