Yes, they would, assuming of course that they agreed that it infringed. The question is, why does SCO want to prevent them from doing so?
Replacing infringing code would in no way remove the evidence of infringement. The developmental history of Linux is a matter of public record, available from many sources around the globe. The Linux community could not expunge it even if they wanted to. In fact, one of the spurious claims of infringement (the memory allocator) was based on code that had already been removed from the most current version of Linux.