In theory powershell 6.0 relies on .NET Core which is also MIT-licensed: https://blogs.msdn.microsoft.com/powershell/2018/01/10/powershell-core-6-0-generally-available-ga-and-supported/
The cited 3-rd party license restrictions are for .NET which is not really "INCLUDED" in pwsh. But this is my interpretation, so I have asked upstream to clarify. Paolo