We patch a lot in the kernel, and it really doesn't matter for us open source / closed source for most of the minor things.
I guess if it is portable to 2.6.18 kernel as well, and we can port kernel changes to prevent creation of hard links to files owned by someone else to that kernel -- it might work for us.
What I would need to research first though -- if any control panel installs symbolic links to files owned by root into virtual hosts that are not for end user (like for webmail, etc...). If they do -- this solution would break it.