Spoilers: "The contents of the message are redacted, but the plaintiffs say [...]"
The email may well prove that Microsoft has this plan, I certainly wouldn't put it past Microsoft. It is in the established nature of Microsoft to behave in such anti-competitive ways, the shoe fits. But when the plantiff is using circumstantial evidence to deduce what the email must have contained, I think it's quite a stretch to say the email "proves" anything.
The email may well prove that Microsoft has this plan, I certainly wouldn't put it past Microsoft. It is in the established nature of Microsoft to behave in such anti-competitive ways, the shoe fits. But when the plantiff is using circumstantial evidence to deduce what the email must have contained, I think it's quite a stretch to say the email "proves" anything.