What an absolutely horrible change. Adding to what Karst said, imagine a giant fleet of Hogosha Samura Liners in Bretonia pirating BAF to join sair side without it being considered a gank. (A certain Werdi did this with one Hogosha liner, lol, imagine 10)
The semi-combat capable trade ships you put in are wholesale useless if this rule is allowed to stand. Bulwark/Longhorn and so on. You might as well fly a 5k or Barge if you are going to get pirated by 6 bombers anyway with no chance of winning or getting away, might as well maximize profit.