It is used only for administration, serial console for a few devices, crunch some log files, etc. It used to be a backup mail server as well. All well within it's capabilities. It isn't likely to run at high load very often. The run like a tank feature is it's primary reason to be. Since it is the machine used to diagnose problems, it's helpful that it is unlikely to be the machine with a problem.
Sometimes, old used equipment is exactly the right answer, sometimes it's a terrible idea. The production servers are much newer machines.