Was the Norwegian Prime Minister's post removed because she posted the image again in that post ? This is a crucial question and not clear from the article. If Facebook censored only words then this is a much larger issue. If they censored the whole post (including photo) then while debatable this is Facebook's policy i.e. a blanket ban on such imagery, irrespective of history.

Edit: I don't find it clear journalism, but the fact is there:

Solberg was one of a string of Norwegian politicians who shared the iconic image after Facebook deleted a post from Tom Egeland

So the post was removed because it had the image, not because she had dared to criticize FB.