Terrorism or Work-Place violence?

During "analysis" of the recent mass shooting, a contributer asked what I believe is a critical question that points this event more toward terrorism than work-place violence: Why would a mother (not the employee) leave their 6 month old daughter (as well a being currently pregnant) behind to participate in a violent attack where her life was at risk if not for ideology?

Combine that thought with the explosives and other materials found that shows "some degree of planning" and this looks less like an act of passion and more like a planned act of terrorism. It may have been triggered by an event at the work-place (although, who drives to a Christmas party with their wife in an SUV filled with assault weapons and body armor?), but the couple clearly considered some "action" and prepared for it.