Good for you!!
So, why you can't use any data coming in from any system for non-security related information/analysis??? Is there anything special about security data? no it's just data=information and nothing more. Of course it has been geared to seeing more security related things but that is just the configuration.... You could probably delete all the McAfee rules and turn the SIEM into what you want it to be... That is way extreme but if you had the $$$ and the talent the sky is the limit.
If you can parse it with a special rule or modify any existing rule to do what you want.... you are in business. You can add your own custom data types populate the fields among the many things the SIEM.
Remember, a SIEM has to be monitored to be tuned properly ... the more EPS the more of both are needed.
That is my quick 2 minute short answer
In response to your Other question..... "splunk to Nitro" 4th result in google points to this Forward data to third-party systems very useful looking page so if you have a product in mind or something you have already it might be in the docs. Also, check this document --> http://www.mcafee.com/us/resources/data-sheets/ds-siem-supported-devices.pdf
The real downer of it all..... If you have to ask McAfee to create a parser or add-on feature via the PER system which many folks have waited many months with no response at all which could put a grinding halt on part of your effort.