Maybe the situation just doesn’t call for use of a triggering word for the same reasons why swear words are less effective when used casually or arbitrarily in many situations. The meaning attached to the swear word is literally derived from the absence of its use in normal daily situations. In turn the use of the word alone is triggering for most that participate in this established convention - that’s the intended design for their use of the word. There’s plenty of forums where exclusively adults talk to eachother without swearing or where a blunt reference to SA would be weird.

When conversation about these topics is warranted, the person tabling it might feel compelled not to trigger other participants and self-censor as a measure towards that outcome. This might not actually prevent victims of SA from being inherently triggered by any discussion on the topic, but it at least signals to them that the organisers of the discussion have considered / are sympathetic to their position, which may encourage their participation in a way that enhances the discussion.

Personally I participate in communities where this topic comes up often and due to the established convention for the mode of discussion in that community, it sounds quite grating to me when someone uses the word rape, because I understand that convention and that it was established for the benefit of others (SA victims), not me.