Interesting. So from Amazon's perspective, it is perfectly fine for a SKU to refer to two products from entirely different industries? I'll admit that I'm not an expert here, but to my mind, a SKU should be akin to a GUID.
For the case you are listing, I would absolutely say that there should be a new SKU, because it is a new product whose quality assurance is entirely disconnected with the original product. If it is only a component rather than the entire product that has changed, I could see there being variations listed with different sub-values, but any review should then be listed with the exact ID that was being reviewed.
I'm of the opinion that any change to the product must be clearly communicated, even if it doesn't change the listed features, because there is an implicit statement that two identically described products are identical. I ran into this a few years ago, after passing down an old desktop to a family member. They needed wifi access on it, and I recommended a USB dongle that I had previously used with that computer. However, the newly-purchased dongle didn't work, because the manufacturer had switched to a new chipset without changing the listing, and that new chipset wasn't supported by the OS version I had installed.
I know that "compatibility with Linux kernel x.y.z" wasn't an explicitly listed feature, and therefore it didn't fall under the strict interpretation of false advertising, but I still consider it to be fraudulent. It was marketed as being the same as a previous model, but didn't have the same functionality as a previous model.