Looks like they're trying to make it disappear, but it's in the wild now.
This exploit is cool but there are similar exploits discovered in any given year and nothing really reeks of a backdoor; this one seems to be gaining attention mostly because Microsoft’s robo-call level initial response caused the researcher to dramatically crash out.
As far as we know, having TPM+Pin or TPM+Startup Key breaks the exploit. TPM only was always known to be basically ineffective against threats like laptop theft, TPM only would only protect you if the drive was stolen out of the machine, which in that case, this exploit also would not work.
Wonder if they knew about this.
If for example a laptop like that gets lost or stolen, the attacker has the data and the key, in a box they physically hold, with no attempt limit, and unless they actively mess with the boot process, it will happily load the key into memory for them. If it's a discrete TPM the attacker can likely sniff the key on the wire. If that doesn't work, they just need to find a vuln anywhere in the secure boot process, or in Windows, and again, they have the key. And if that doesn't work, they could sniff the memory bus, or do a cold boot attack (again, with unlimited attempts unless they irreparably damage the mainboard/TPM in the process).