I don't think Microsoft feels threatened by desktop Linux. If it catches on, it will be because manufacturers start shipping it, not because it's easier to install.

Manufacturers sell Linux workstations designed for power users and developers. UEFI/TPM, and now Pluton won't be a stumbling block for that as it hasn't been so far.

Dell is the biggest seller of pre-installed Linux desktop machines, and they are all billed as Workstations for power users or developers. Their home machines only have as an option Windows or ChromeOS. (Count that as Linux if you like, but I wouldn't...)

Why? Being more price competitive by bundling a free or cheap OS is not worth it in scaling up their support for a new OS. That's your stumbling block to better Linux desktop adoption, in my opinion.

Causing issues with remote attestation are probably more a side effect of just not caring about other OS's, rather than some sinister plot to sink Linux on the desktop.