What does and what does this MICROSOFT REFERENCE SOURCE LICENSE (MS-RSL) grant or prohibit?

Question

Copyright

My client recently quite foolishly said that he was transferring the entire project to this license.

And he asked for two authors:
The author of the idea - the client the
author of the code - me

But he wants to remain honest and transparent with his clients, that they can ask for the source code upon request from him and make sure that there is nothing there that could pose a danger to their privacy .

And secondly, he also doesn’t want to fully open the project code, he is afraid that they will copy it, steal it, since he wants to earn at least something on his product.

What is it and how to work with this license?

But to be

Answer 1

https://referencesource.microsoft.com/license.html