I'm sorry but that is pure BS. By what mechanism do you think this is likely? Win8 has been out for free for anyone to test for months now and I haven't seen anything even hinting at a compromise published. The boot loader is a small piece of code and auditing it is a completely tractable problem. Maybe you haven't noticed but MS has gotten religion about security in the last decade and has some of the most thorough auditing of any software project.
This is just a fancier way to make the statement "Linux rulez and MS droolz" which isn't a useful statement.