I get your point and like the fact you’re making it. Love the spitting image finalé by the way, nice touch.

But, as has been mentioned by others, the caret is a little ambiguous and does not instil confidence in the following action for user as it has very little affordance.

I wouldn’t want to propose a generalised solution without testing, but it is a broken concept. So, I think moving the save button to the location of publish would be a stronger CTA with confidence and lower cognitive friction or possible mistake. Aligning a publish button to its left–to increase the conscious effort required to publish perhaps may help. Also, following the action perhaps a timer (countdown/undo period ala apps like gmail [when enabled] — I certainly do). Then the publish button replaces the save for follow up edits. This may all be overkill or not. The timer would probably solve the oh £$@! moments. That widget box related to post/page actions could definitely be better configured and with the pace of WP development, I am sure at some point it will be :)