Huawei almost certainly is considered a national security threat by the NSA/GCHQ because they don't have influence over them so can't add exploitable bugs/backdoors to their kit.
Whether Huawei adds such features for the Chinese security services is another issue but why would we expect the Chinese security services to be behave differently to the Americans/British?
Regardless of the rights and wrongs of what the security services are doing, I think that when you're buying critical infrastructure for your emergency services, it's entirely sensible to restrict the potential vendors to the ones who are open with your security services.
Biting the hand that feeds IT
