Did you read the author's first paragraph:
So why do you want to install yum on a rhel box if you already have up2date for RHEL4? Well there are a number of reasons, the main one and the reason I wrote this is that I was installing openvz and it needed yum installed. Trying to just use the yum rpm or source compiling was getting all sorts of python errors. I decided to just grab the centos 4 rpms. Note this is not going to be used for updating, up2date still is used for that.
Originally Posted by saak.stepi
A couple of days ago I ran "yum update" on my RHEL4, x86_64.
yum updated a whole banch of old packages and installed
some new packages.
You probably shouldn't have done that. It sounds like you updated RHEL4 with packages from CentOS's repositories. I'm not sure what sort of bizarre state your applications are in at this point.
If it were me, I'd take it as a lesson in 1) reading the directions carefully; 2) maintaining a healthy skepticism about "howtos" found on some dude's blog (or whatever it is).
I'd recommend taking backups and reinstalling RHEL.