Is the reluctance to discuss the war after so many veterans return home, a consequence of their deep trauma, or is it actually mind control manipulation?

As you saw intuitively, this is almost entirely mind control manipulation. Without that suppression, there would be indeed many references to the tough things, the tough times, the darkness. It can certainly be referenced to make a point without telling one's whole life story and going through the gory details point by point, moment by moment, to re-live them, in a sense. But the sheer totality of the clamping down and keeping silent totally to the point of avoiding direct questions and even having to leave the room are all signs that something more powerful is at work. It is unnatural but dismissed as the consequence of an unnatural situation, namely, the war experience, but that is a superficial explanation. The true reason for such behavior is that the veterans are programmed to remain silent of all that happened. This is exactly analogous to what is done to the former members of the so-called Secret Space Program but without the suppression of actual memories of the experience itself. These include many restrictions on what can be shared and why, as well as admonitions to avoid discussing many subjects. This serves the Extraterrestrial Alliance by contributing to the passivity and the naïveté of the general population and especially, the up-and-coming newer generation being subjected to a culture that treats war as a noble aim when on the side of right, without any deep analysis of the moral implications and the divine perspective, anything that would disenchant the young and perhaps hinder new volunteers to die for the cause. And so, chaos and suffering would make the job of the Extraterrestrial Alliance more difficult by hindering their ability to sow chaos broadly.