Don’t entertain meetings without compensation from megacrop. But the project is open source. The author provided the right for them to take it in any way possible and copy it. If I’m not mistaken the MIT license allows what they did.
I’m assuming the complaint is more about Microsoft duplicity in asking for information as opposed to the forking of the code. The latter is fine - the license explicitly allows it.
The "notice" is the literal license file. It is illegal to strip someone else's license from their work. It doesn't matter that they replaced MIT with MIT, because they stripped the author and attribution from it.
Peerd seems very different from Spegel, so Microsoft does hold quite a bit of copyright over Peerd.
Now I genuinely wonder if the main LICENSE should say "copyright Spegel and Microsoft", or if somewhere in the repo Microsoft should just have a copy of the Spegel LICENSE file?
a) Keep any code that you've pulled in from another project in its own directory structure with a license file indicating where it came from and its licensing terms.
b) If you intend to modify the code or integrate it more tightly with your own, copy the notice into each source file that was taken and perhaps put a pre-amble along the lines of "Portions of this file were copied from XXX under the MIT license as follows:". Ideally you would make a commit with the file in its initial state as copied, and then if you ever need to determine what came from where and how it was licensed, it shouldn't be too difficult.
Generally, what I take from this discussion is that what you want to do is get as much inspiration as you want from the code, but absolutely rewrite it from scratch such that it is yours and yours only.
What you're proposing, updating the license file to list the authors, is a pretty common way to do this. It does mean that the code is mixed a bit, so it would be hard to split who owns what, but this is only relevant if one of the copyright owners wants to change the license (as they can legally only do that to the code they own).
It looks like they relatively recently migrated the entire codebase from Apache to MIT. I wonder if that was in relation to pulling in code from Spegel. They updated ~every header.
I’m assuming the complaint is more about Microsoft duplicity in asking for information as opposed to the forking of the code. The latter is fine - the license explicitly allows it.