My understanding of a 'trigger' is that in some way the thread contains content that leads a poster to remember or think about a traumatic situation they themselves experienced.
It would be fair, I presume, to think that any mention of abuse by a partner may trigger a stress response in someone who has experienced DV, even if the details don't correlate.
But the way the usage had evolved on MN seems to be 'trigger=unpleasant' or 'trigger=upsetting', which I think trivialises the reality of a true 'triggering response'.
Taking an example of a child at the hands of a parent. It's upsetting, incomprehensible even. But I doubt it could truly be 'triggering' unless you'd experienced, or knew in detail of anoanother incident. For example, if you'd served on a jury in asimilar case and were badly affected by what you heard and saw, it could be triggering, but in most cases it's just upsetting.