In my view, it is absolutely about security, and much more broad than "spying."
China is absolutely an adversary of the USA. If you give your adversary control of a national asset such as the entire wireless network, then you are a fool. I am no fan of Trump, but holy crap did we allow our security interests to get dominated by business interests in the past.
One great example is that for unknown reasons, we allow Chinese POPs in Canada, however there is certainly no western POPs allowed in China. Here is a story about Canada-to-Canada data being routed through China via a Chinese POP. [0] I remember it being discuss on HN, but now I can't find it.
[0]https://toronto.citynews.ca/2019/01/31/israeli-cyberexpert-d...