When you know you have a backdoor you may take some steps, small as they may be, to protect yourself. For example in some cases you can remove the ME blob from the BIOS, effectively disabling the ME. You can choose to drop the product entirely. You definitely can't protect yourself from something you don't know exists.

Considering nation state actors have been consistently backdooring everything they can get their hands on (network equipment, CPUs, software, storage devices, you name it - and they've done it without the manufacturer ever knowing sometimes) the assumption that such an open source project would not have it and it's "a lot better" is based purely on wishful thinking.