You know, you are on a site devoted to Star Wars, so calling this subtle difference “obscenely revisionist” is taking it a bit too far. Now the Star Wars SE, DVD, and blu-ray could be called obscenely revisionist, but what Cameron has done to Titanic involves minor tweaks of the sort I wish Lucas had made to Star Wars.
There’s nothing “minor” about digitizing the whole film from the camera negative and then re-compositing everything. By comparison Blade Runner was digitised from the camera negative for the unedited shots, and from the master positives or intermediate negatives for all the shots with optical effects. And that’s standard now for a 4K remaster.
But I should note there was absolutely no reason to do an extensive restoration for a recent flick like Titanic anyway, all they had to do was scan the o-neg, grade it to the print, and release it. Easy peasy.