Ah, once again Microsoft is the one that supports less security than the other major companies. Microsoft needs to distance itself a bit more from law enforcement agencies.
I got the impression that Microsoft is backing this because of pressure from large enterprises, which do not want to deploy TLS in their intranets. I don't believe IE will prefer plaintext HTTP/2 to TLS HTTP/2, and it will certainly deploy both.
Put another way: I don't believe Microsoft is worse than Google in this regard.