If it gets us closer to being able to run native Office and Directx apps on Linux I'm all for it. Snap enforcement already scared me away from Ubuntu for the most part anyway.
Were I Microsoft, a custom Linux would be exclusively for server side benefits. Better/more integrated Azure tooling, native VS Code Remote Development containers, improved telemetry, native account/security provisioning, etc. No reason to tempt fate with better cross platform desktop efforts.
This would be self-sabotage for Microsoft, it erodes their moat. If they actually cared about user producitivity and making those specific products as widely used as possible then it would be reasonable for people to expext this, but that's not their real goal. Acquiring Canonical changes nothing about their ability to make this happen, they could do it today, but their corporate strategy forbids it.
Microsoft already has WSL2 so they can already run Office and Directx on the same box running Linux. I'm not sure that they have an incentive to make people run Office natively on a real Linux desktop. Wouldn't that lose some Windows customer? I think Office 365 already runs in browsers also on Linux but I never had a reason to check.
