That depends... If root is dumb enough to mount/umount something in user-modifiable parts of tree with users present, you are screwed anyway, symlink attacks or no symlink attacks. Just Don't Do It(tm), on any Unix.
If you are allowing non-root mounts, you need to be damn careful; it *is* possible to get it right as it is. Variant that doesn't follow symlinks makes some parts of that slightly easier; it's not a big simplification, but it makes sense and it is useful.
Whether your suid-root mount wrapper of choice is getting it right or not is a separate question, of course - all software sucks and all such.
It doesn't close any existing security holes (if nothing else, existing binaries behave as they used to) and it's not as if it was providing means for closing a hole that would be impossible to close without it.
So whether you call that fixing a security hole or not is up to you. Commit message is a bit too strong ("needed for" != "makes it easier to") and TFA is even stronger than that. The former hadn't been too far over the top and I didn't feel like editing it. As for the latter... questions to the article's author.
Here begins the countdown to wankers splashing out in force, screaming "coverup" and "conspiracy"...