The "risk" mentioned in the quote a few comments up, and in the context of the post by MSRC, isn't about the risk of leaking Microsoft IP. It's about the risk that Microsoft customers might have been affected. Whether or not MSRC found evidence of a breach of customer accounts/data is a related but separate question.
Please note: the source code of Windows 10 can be requested if you are a large enterprise or a government already (as long as you agree that you won't release it). The only possible significant difference here is the lag - you can read the source code of the internal builds, whereas you can only access the corresponding source code for stable builds officially. So, if you are a government, you can actually request it for a legitimate purpose and pass it into the other side of that government if you really want to.
The "risk" mentioned in the quote a few comments up, and in the context of the post by MSRC, isn't about the risk of leaking Microsoft IP. It's about the risk that Microsoft customers might have been affected. Whether or not MSRC found evidence of a breach of customer accounts/data is a related but separate question.