I was going to say that the patch is fine as it does not actually refer to details of unreleased operating systems (i.e. the code using numeric version comparison is correct whether or not 10.10 ever gets released).

However, some changes do refer to such information, e.g. knowledge of the format of MACOSX_DEPLOYMENT_TARGET. I'm generally -1 on committing such changes. As you say, the system vendor may change his mind (and e.g. chose to release the system as 11.0 instead of 10.10, because of issues with two-digit subversion numbers, in which case your change would be incorrect).