It's not about what's factual, the guidelines are pretty clear:
> Please use the original title, unless it is misleading or linkbait; don't editorialize.
> Please use the original title, unless it is misleading or linkbait; don't editorialize.
> Otherwise [outside a set of very specific circumstances], please use the original title, unless it is misleading or linkbait; don't editorialize.
I'm not sure what would count as "specific circumstances". One could argue though that the original title was "editorialized", since GitLab has an incentive to soften the blow of the news, especially since the original title doesn't tell much about the news itself (what is the important update)?
The exceptions are (1) if the title includes the name of the site or (2) if the title begins with a number. Neither apply here.
I believe they phrased it this way so some discretion can be exercised if the original title doesn't give the full context. Another example is the recent Tesla story - original title is "Q3 2019 Update", story title is "Tesla Q3 Financial Results". The HN story for when MS bought GitHub is "Microsoft acquires GitHub", while original title was "Microsoft + GitHub = Empowering Developers".
If there wasn't such a leeway, most acquisition stories would be titled "Our incredible journey".