Speaking of MS OpenTech, people just don't understand what it is (or rather, was) about. Back when MS was still in the "dark ages" wrt open source, but slowly coming out of them, OpenTech was set up as an independent org that could work with open source without the fear of "contaminating" MS proper - remember, this was back when Ballmer with his "GPL is a virus" notions was still around, and lawyers were super-paranoid about people copy/pasting some code snippet and inadvertently exposing the code to some OSS license, or a patent claim or something like that. They were even more paranoid when people wanted to contribute something upstream; with a few exceptions, this was something that you had to go to OpenTech to do.
Now that this is no longer the case, and regular devs inside MS are allowed (in fact, actively encouraged) to use and contribute to open source, the legal separation that was the whole point in the first place has lost its relevance. Notice how the announcement specifically notes that this is not about laying people off, just closing down the legal entity.