Not just B2B, but the business must be “Seed, Series A, B, or C stage (or validated equivalent)” funded.

I’m not entirely sure what “validated equivalent” entails, but I take it to mean they’re interested in VC-funded companies, not bootstrapp{ed,ing}, angel-funded, or crowd-funded companies

Your acquisition hypothesis seems quite likely to me; it would be naïve to believe that Microsoft would offer such value out of the kindness of their hearts.

I don’t want to sound bitter: If one has a business that qualifies and is okay with adopting a Microsoft stack, it seems like a great value. However, let’s not give MSFT too many PR creds for being a selfless charitable organization who is ‘looking out for the little girl’ in business, because they’re simply not. They’re a for-profit corporation.