This seems like very odd logic as if followed through, we shouldn't allow any drivers into the kernel. Every driver in the kernel has the express purpose of making a proprietary piece of hardware work in Linux, whether coded by the manufacturer or not. The truth behind your statement is exactly what Linus was referring to, the "M$ Disease." Simply because it is Microsoft you feel the complete and utter need to bash it. No rhyme or reason. Defies all logic. It just must be done.
This is a great step for the Linux community. I doubt very few people would believe that Microsoft would ever become a contributor to the Linux kernel. They have made an investment now in Linux. That is quite monumental. Those 20,000 lines of code weren't free and they will likely be continued to be maintained. This is an exciting time!