My understanding is that it wasn't introduced by TSLRCM. Rather, it was considered for the original game but cut due to time constraints. It was one of many ideas that hadn't been fully explored by the writers, and could easily have been rejected outright or added as an alternate path based on previous choices.
tl;dr
An unfinished game doesn't exactly have a canon.
Okay, "TSLRCM addition" might not be the right term. I intended to mean it was a content that didn't exist in vanilla TSL but was restored by TSLRCM. I assumed that people would get that due to the nature of a restored content mod, most if not all content from TSLRCM were cut content that wrere originally considered by Obsidian and not introduced by TSLRCM.
Regardless, my point against The Historian's claim that the confrontation wasn't "historically accurate" to Meetra Surik's story still stands. Unless there's actually an official source, SWTOR or not, that proves that it didn't happen, arguments about it not being "historically accurate" is invalid.