It is not, however they have made enough contributions upstream, so the project is tainted for those that don't have anything to do with the reasons described on the post.

Which by the way, is shared across other corporations adding code into Linux kernel.

Or do we only stand by morals when it is convenient?

Although they have made contributions, they do not control the project. By using Linux, I am not helping Microsoft get more money or exert more control over the tech world.