Twitter - Inconsistent in their lack of censorship?

I don't use Twitter and am therefore not that familiar with it. I thought this tweet by ex Malaysian Prime Minister absolutely appalling in the wake of the Nice Cathedral massacre of innocent people.

This is the tweet "Muslims have a right to be angry and kill millions of French people for the massacres of the past" an incitement to violence surely??? I believe the tweet was merely labelled with a wishy washy disclaimer by Twitter stating that the tweet in question "violated it's rules about glorifying violence" but nevertheless adding " it may be in the public's interest for the tweet to remain accessible" Following an overwhelming public condemnation the offending tweet was removed, but why was it allowed to be put up at all in first place?