It's not semantics. A true bitlocker backdoor would let you in even if it's passworded.
And is it really downplaying? The ability to shove in a USB stick and get control over the drive is mostly equivalent to a bitlocker exploit when it comes to laptop theft. But for quick access to a desktop without bitlocker, and without the ability to open it and pull the drive, it's actually more damaging than a bitlocker exploit.
2) I am not personally being dismissive of the claim. I'm saying it's fine to hold off, and even if we assume the PIN version is real we shouldn't assume we know exactly what it looks like.
3) Saying it's not a backdoor distracts from the point? Can't agree with you there at all. The comments saying it's definitely a backdoor are the ones I point to as distracted.
4) Maybe it's downplaying but it's true. Replying on TPM-based bitlocker is a lot more dangerous than having a secure password. It's chosen because it's easier to enforce.