I've said it before, but while I use these brands of cameras on my personal network and don't have anything to fear by doing so, I am also 100% in support of the ban.
Regardless of the political motivations for passing this ban, it actually does help improve our national security. I know a lot of people would argue that a properly set up network would prevent any harm from using these cameras (which is why I use them on my personal network), but that is a short sighted concept of the level of network security that our government and other sensitive faculties needs to be applying. Just look into the Stuxnet virus to see how advanced electronic warfare can be - especially from state sponsored groups that have the money to accomplish almost anything. Stuxnet was a single purpose virus that worked it's way into a secure facility and onto a completely isolated network (ie zero outside connections) without the hackers having physical access to the facility. Imagine how much easier it would have been to accomplish if the hackers could have loaded the virus on a device that was going to be installed in the facility - by the very people who ran the facility! By allowing these cameras into government and other sensitive facilities, we are potentially installing a real trojan horse that would make the hackers job that much easier. The hackers are state sponsored and the companies are (at least partially) state owned - it absolutely could happen and the ban is designed to be just one more layer of a very complex security scheme.
But in case I wasn't clear in the first part of the post, I have no problem using these brands in personal/private networks. This use is not going to be the intended target of a Stuxnet type attack and therefore there is no real risk as long as the devices are isolated on your network (ie they have no access to the internet of the rest of of your network).