The email is also from 2019. It might still be worthwhile evidence, but it wouldn't really pertain to the Activision deal in particular.
If someone at Microsoft had sent an email a month before the Activision deal saying, "we want to crush the next-gen Playstation," that could be evidence that the Activision deal is part of a plan to monopolize the market, but it could also simply be somewhat random nonsense puffery talk like when someone says "our graphics blow away the competition!" Given that it was sent back in 2019, the distance in time from the Activision deal makes it potentially less relevant.
The allegation is that the email is "uncontroverted evidence that Microsoft had the intention to put its main competition, the Sony PlayStation, out of the market." What I want to know is whether the email is a somewhat innocuous, "we want to relegate the PlayStation to the status of an also-ran while we become the premier gaming console" or something more serious like "our strategy to drive Sony out of the market is by buying up independent publishers and then making their games platform-exclusives to the Xbox." For the first one, I'm sure I could dredge up communications at any company that are similar. For the second, it shows a clear danger to competition and the market.