As we all know from finance 101, debt holders have a material stake in the debtor company. Of course if this stake is high enough, the creditor can influence strategic decisions albeit quietly. As has been suggested elsewhere, this was Microsoft's play in financing $2 billion of debt in Michael Dell's play to take Dell computer private. (We'll see if minority shareholder lawsuits allow the deal to go through.)
This is an interesting play by Microsoft, and I think broader than a defense of the lucrative PC ecosystem. That defense is only a medium term play by Microsoft. Although the consumer PC ecosystem is lucrative, it isn't growing at the rate that mobile is. I believe that that is where the true value is. The Microsoft Surface is not a bad play. The UX of tablet + keyboard is a great concept. Of course, the early reviews of Windows 8 as a UI are not good. On the other side, Dell surely wants to enter the tablet market. And Michael Dell wants to gain all the equity he can before that play is made. Furthermore, that transition likely requires more control and discipline than the quarterly ups and downs of the market would allow.