In the video scheduled to be posted on YouTube apparently there were more elements (talked about their own dressing style and not feeling either a man or a woman - according to some articles which translated the pages in russian).
I think this is overall irrelevant anyway. In their manifesto they go all over the place ideologically, from holocaust praise to trans rights, apparently. It's not like there was a consistent motivation behind, they were clearly unwell mentally - reporting depression and suicidal thoughts for years - and did the shooting to be killed.
https://proton.me/blog/lumo-security-model
Yes, the model will need the data. They have a good page about this.