Hi Edwin,
SEP is chiefly a Windows defence system, though it does come with some Mac and Linux software.
Malware authors want their threats to spread as widely as possible. So, they typically craft their code to exploit known vulnerabilities in the most widely-used OS's: generally that means Windows, though in recent months there have been a lot of threats for the popular Android OS and FakeAv for Mac. See these Security Response blog posts for more info:
https://www-secure.symantec.com/connect/blogs/i-dont-use-av-because-i-have-mac
https://www-secure.symantec.com/connect/blogs/droid-dreams-reoccurring-nightmare-android-users
There are some threats that specifically target Linux (for instance), but off the top of my head I am not familiar with any that target the AIX OS.
For your AIX server, the product you probably need is Symantec Critical System Protection. Symantec Critical System Protection 5.2 is intrusion detection software that protects against day zero attacks, hardens systems, and helps maintain compliance by enforcing behavior-based security policies on clients and servers. A centralized management console enables administrators to configure, deploy and maintain security policies, manage users and roles, view alerts, and run reports across heterogeneous operating systems
System requirements:
IBM AIX 5L (version 5.1, 5.2 and 5.3)POWER PC platform
100 MB free disk space
256 MB of RAM
Hope this helps!
Mick