What are the reasons to favor one specific vendor giving it a key advantage over the other? Microsoft seems to be clearly playing favorites here. What are they trying to do? Give a monopoly to their favorite vendor? Is it legal to use your monopoly to expand someone else's? Can we really call this company, with its seemingly deep and strong ties to Microsoft, a separate entity? If it's not, this is clearly something the DoJ should look into.

"Use your monopoly"? What monopoly is Microsoft using?

That over the Windows desktop. There's nobody else you can get a license from.