I don't think anyone needs to prove malfeasance here - a threat to national security doesn't require wrongdoing, only the existence of attack vectors by a foreign hostile nation/entity. Publishing those attack vectors would be a hilariously terrible idea as it would have ramifications in every country with Huawei in its infrastructure. Plenty of products are deemed essential and produced domestically or only by close allies, this goes for just about every country, I'm not sure why communications infrastructure is somehow different.
The US already has secret and higher security internet networks for the communication that is deemed ‘essential’. And I would bet there are no products that have not gone thorough vetting deployed on those networks.
