If it is as universal as you seem to suggest, why no action against him?
Also, I never claimed it was right wing trope but I was pointing out that the quotes you gave were all opinions as to whether it was in breach. If they were facts then surely something would have been done. However...
But in spite of the above, GB was not sanctioned by the UN for the war and nobody was prosecuted because they are all interpretations of the law!!
As for getting the UN Security council to agree, that was never going to happen under any circumstances as Russia would have vetoed any resolution...