“Fifth column” refers to citizens or residents of the targeted country who betray it to an invader. Your concern would be well-placed if this were about Americans of Chinese ethnicity. But it isn’t; it’s about citizens of China “visiting” the US and probing security of US military facilities.
Again: This is about citizens of China, not Americans of Chinese ethnicity. And it is not just about any citizens of China visiting the US, but specifically those who attempt to get into US military installations.
Citizens of China are expected to obey the Chinese law requiring them to assist the China regime’s spy agencies. If they don’t, they and their families can be imprisoned, tortured, or murdered. None of that is true of Americans of Chinese ethnicity, nor do these articles suggest that it would be.
So I think your concern is misplaced here.
The US has made that mistake in the past; most famously in WWII with regards to Americans of Japanese ethnicity. That was bad; that was racist; that was unjust.