Because nobody would lie on the internet? Look at the post history. They don't even live in a location with a Microsoft development house.

The poster has posted a bunch of stuff to a London subreddit. A couple seconds on Google returns:

“Our London office primarily serves the MSN and Xbox teams, although the ground floor is set up for hot-desking to ensure that any of our employees can work from this office when they are in London.”

http://careers.microsoft.com/careers/en/az/offices.aspx#GB_L...

“Microsoft dev” doesn't mean “Windows kernel hacker”