A rootkit is a rootkit. Install one, it has free reign to do what it likes.
The basis of the article seems to have the usual distractions, it was only aimed at very small number of gamers, it was only a small number of customers affected etc, etc. Distraction/obfuscation/mitigation.
Let's not over complicate this for distraction/mitigation for Microsoft.
A rootkit is a rootkit, install one on a machine and it gives whoever full administrative access to the machine, to install further software/malware, hence its name "rootkit".
In the context of Windows 11, that means this rootkit would have got past Microsoft's security, the 'secure' TPM 2.0 chip.
TPM 2.0 is going to generate a lot of landfill for nothing (other than to sell you a new PC, that does the same 'drudge'), if Microsoft still fail to do their job (as in this case), checking submitted code.