I noticed this new workaround in the redhat KB:
Red Hat Enterprise Linux 6.2
Manually Setting a Preferred Operating System Release
Beginning in Red Hat Enterprise Linux 6.3, Red Hat Subscription Manager could set a preferred operating system version to use to limit automatic updates for a system. This is covered in Section 5.7.4, “Setting Preferences for Systems”. However, it is not possible to set a preferred operating system through Red Hat Subscription Manager on older versions of Red Hat Enterprise Linux.
The system can be restricted to a certain operating system version on Red Hat Enterprise Linux 6.2 by editing the yum configuration. For example, to limit yum updates to 6.2-version packages:
[root@server ~]# echo 6.2 > /etc/yum/vars/releasever
Update: the above did not work for me on a new install of 6.2.