I don't expect it to be suspicious or odd _in China_. What I am saying is that internationally we should not just shrug it off as "aww, it just China, they're always so sneaky and secretive even when it's nothing!" We should treat the situation as if they are indeed hiding something important every time, because otherwise, constantly acting suspiciously about everything is an effective strategy for them conceal anything important.
Barring foreign scientists, arresting journalists, and destroying evidence is always suspicious, even if they always do it, and it should always make people from open and free societies curious of why they are doing it, not shrug it off because it's the norm.