Should this be in MSBuild or on the SDK? Meaning, are TFMs a general MSBuild concept or are they something that applies to managed languages/sdk-style projects only? My intuition was SDK-style projects only and so I would have expected to see this only on the SDK layer.

One thing I'd like to check is that it's very common to have a multi-TFM project, but then build or publish for a specific TFM at the command line using the '-f' parameter, which is passed to the build as a global property. Does this usage pattern trigger the check incorrectly?

Should this be in MSBuild or on the SDK? Meaning, are TFMs a general MSBuild concept or are they something that applies to managed languages/sdk-style projects only? My intuition was SDK-style projects only and so I would have expected to see this only on the SDK layer.

I'd keep here now as we do not yet have a good concept of 'friend build-in checks'.
I'm open to complains and discussion though

One thing I'd like to check is that it's very common to have a multi-TFM project, but then build or publish for a specific TFM at the command line using the '-f' parameter, which is passed to the build as a global property. Does this usage pattern trigger the check incorrectly?

Global override is allowed. I put this to help link:
https://github.com/dotnet/msbuild/pull/11062/files#diff-e96bdd5e98d7e8729178bfbea183e2e16e385f10219a0d4121b2043a4883d5d9R92-R96

But it should be more specific and clear - I'll imporove.
Thanks for bringing this up!