> If there was never evidence to anything, then it's reasonable to assume?
In some cases, yes.
For instance, I'm sure China wouldn't build its nuclear deterrent around some hypothetical US-made COTS "Nuclear Weapon Control System," even if there was zero evidence that system was compromised. Absence of evidence is not evidence of absence. Ditto with Huawei.
IMHO, if its decision-making wasn't so addled by wishful thinking and capitalism, the US would use far less Chinese technology for this reason.
First, just saying that something is legally possible does not mean that that's what occurred.
Second, this isn't something China-specific. The US Federal government also has enormous power to compel companies to cooperate in surveillance. Just recall when the US government ordered Lavabit to turn over its SSL keys, so that the government could intercept Snowden's emails.
You realize that all "private" companies and citizens in China are extensions of the Chinese government right? By law, all companies require party affiliation. So naturally, there is no separation between Huawei and the Chinese government.