I suspect that aspect of it is exaggerated. I've been following that topic on Slashdot, and when people ask for proof there are backdoors in Huawei gear, the same links always get angrily provided as "proof" but those links are always complete non-sequiters - usually lawsuits against Huawei for infringing other companies IP. Sure, stealing trade secrets is a bad thing, but I fail to see how it's evidence that the network gear they're selling the consumer is secret spy-gear. Additionally, China uses Huawei gear. A backdoor is a backdoor for anyone, including America.
Also, forensics can look at ROMs and see what's in there. Whatever backdoor you put in there is effectively public record in the wild and you can no longer control it once it's in the physical possession of the other side. The gains to China by having sneaking backdoors in gear they sold are actually worth less than the potential losses they would incur if there was proof of the backdoor being there. And also, the corporate espionage charges against Huawei reveal why it doesn't make a lot of sense. There are cheaper and easier and less-liable means of engaging in espionage, such as social engineering, or exploiting vulnerabilities in other people's gear. You definitely wouldn't want an easily-exploited backdoor in your own gear, and if it was only in the American-sold gear then people could easily get the China version and America version then work out there's something fishy because the firmware is different.