Yes, Hullygully, that is wholly accurate. Well, in my view, anyway; but it's a bit of a mouthful to use that when reporting stories.
If 'so-called' before the words 'honour killings' was used by all the press, then it would be challenging the notion that these killings were in any way shape or form 'honourable'.
Instead of people thinking, 'oh it's an honour killing so it is somehow OK, people would perhaps pick up on the 'so-called' bit and challenge the notion that it had anything to do with honour.
If anybody who believed in these 'honour' killings then complained, it would just be refuted with 'sorry, but our journalist feels that these killings do not, in any way, chime with his/her notions of honourability'. Which is totally reasonable and fair.
Only words at the end of the day, I suppose, but just a few thoughts.