Why not port Linux kernel to Common Lisp?

Conventional wisdom states that OS kernels must be written in C in order to achieve the necessary levels of performance. This has been the justification for not using more expressive high level languages.

However, for a few years now implementations of Common Lisp such as SBCL have proven to be just as performant as C. What then are the arguments against redoing the kernel in a powerfully expressive language, namely Common Lisp?

I don't think anyone (at least anyone who knows what they are talking about) could argue against the fact that the benefits in transparency and readability would be tremendous, not to mention all the things that can't be done in C that can be done in Lisp, but there may be implementation details that would make this a bad idea.

I've a few new ideas for Lisp OS security, which would eliminate even the possibility of writing a virus:

Unauthorized program should't be able to access filesystem or internet. Every program should be limited in access only to files and directories provided by the user, while internet access is given only to programs installed under apps.interned_allowed directory. There should be a way to reject privileges given to file/directory handles, so accessing them would produce exception. Users shouldn't see outside of their home directory and all file-sharing should be explicit. User password should be too kept under's home directory, so it could be changed without much fuzz with /etc/passwd.