Powershell is exactly what bash should be (and this person wants). Their time would have better spent using and improving the pash project (open source Powershell on Mono): https://github.com/Pash-Project/Pash
Powershell is primarily a repl to a homogeneous .NET-based set of tools, which doesn't describe Unix very well. If you want a type-safe repl that interacts with all the handy tools written for the text-stream-only Unix world you're going to have to do some interpretation.