The vendor isn't obliged to make their device hackable even if they do publish the source. Some do, and that's neat, but in most cases, access to the source might, at best, only result in the next iteration of device having some change in a year's time. Your little box will continue to make you unhappy. You should just get a refund.

The kernel developers aren't on the hook at all here. No one told you to buy a specific device.

Oh, thanks, of course you're right.

Except for devices that are hackable in practice, but aren't much so because of this heartwarming attitude.

It's not unusual that someone had managed to build the kernel that boots (and even works well) but doesn't know how to interface some hardware. E.g. a hardware NAT engine of a SOHO router, so FLOSS firmwares have to NAT in software. Or some sensor on a phone. The secret is in the kernel and that kernel's source's supposed to be available but it isn't.

The GPLv2 has absolutely nothing to do with the EULA for a product.

Your beef is with device vendors, not Linus.

Here, we don't talk about the product itself, as a whole. We talk about its kernel.

Sure thing, if I don't have access to the kernel, then it's all irrelevant. We only consider the cases when the device is actually hackable (despite whatever its vendor says).