There are many reasons to distrust Microsoft. The wording of this particular paragraph explaining how data gets used in accordance with the linked terms of service (which are the actual governing documents, not the page you’ve linked to) is not one.
I agree that the particular wording is not sufficient to specify much of anything, but does it sure doesn't shut the door on the possibility either.
Unless you can meaningfully show that Microsoft is actively applying a subsidiary relationship (that is, where it directs OpenAI’s product direction), I have to disagree with your base notion.
At this point, I reiterate that your original claim is 100% FUD and disinformation.
I’m not asking you to trust GitHub or Microsoft, but legal terms have meaning and the terms do not support your assertions.