Bluntly, I don't care about the "morality" of a PRC supplier. What I care about is the inherently untrustworthy nature of the hardware.
It is a phone running PRC coded firmware running on PRC assembled hardware with PRC produced components throughout. More, it is a device inherently targeted at the high end western market and, with GOS, at people of intelligence worth. If the MMS doesn't compromise the hardware and/or firmware then they aren't doing their job.
In addition, Lenovo is a PRC headquartered corporation. Under US law it is a righteous target for the NSA and CIA to infiltrate and compromise. If the NSA backdoored the Pixel that would be blatantly illegal under US law, a massive political scandal if it came out, and very likely to be leaked. The exact same thing done to a Motorola flagship is just top flight intelligence work with basically zero potential downside for the NSA or CIA.
Can you guarantee that the Motorola isn't going to detect at the firmware level that GOS is installed, copy the encryption keys from the secure element, wait until the phone is on a mobile network with a usage pattern that replicates actual real world use, and then sends the data back to a PRC controlled server? Because that is a serious and realistic concern.
With Pixels and Google, that risk is essentially non existent.
Don't get me wrong, I'm thrilled to see broader GOS adoption and more hardware support. But a PRC OEM is going to have a massive mountain to climb before I would trust their hardware for anything security and privacy focused. At an absolute bare minimum, they would have to give the GOS team full firmware access before I would even consider a purchase.