Ok! So I asked friend about this and I'll try to explain best I can!
It is do do with how search terms work individualy. Searching 'women' should only bring results of women on the first couple of pages because trans has not been included in serch terms. The example he gave was the search term 'loans'.
In 2016 google worked against the main results of the search term 'loans' bringing up pay day loans because unless you specifically searched 'pay day loans' the main search result should bring up only regular loans if you get my meaning. He suggested that pay day loan companies had tweaked the algorithms to attach to the term 'loan' despite it not being included in the search terms. The only exeption to this is advertisements.
In short, while google search does work to an extent on popular searches. The conflation of 'trans' with 'women' shouldn't happen without that term being included in the search which suggests that the algorithm has been manipulated.
However, he also agrees that the topical nature of murdered trans women also plays a role...while in theory, searching for women murdered should bring up just those terms. Trans women murdered would also be included in further pages un order of relevance to original search tterms
In order to conflate 'women murdered' with 'trans' you would search original term then search further through the less relevant results to find 'trans' examples. The more these results are clicked the more google conflate the terms as relevant.
Additionaly! (IKR! My brain hurts) google will also search through your browsing history/cookies to personalize the result to you. However, I cleared my history, cookies and went incognito but the terms trans and women were still conflated.
Interestingly, he noted that prior to 2015 these search terms had not been conflated. Make of that what you will...
He also suggested that there are ways to address this conflation of search terms...though it went a bit above my head 
I hope this all makes sense...am going for a lie down to ease my hurting head