I'm thinking that he deliberately chose one city that's pretty much guaranteed to welcome him and his message with open arms (Dublin), one that has a shitload of zionists AND uncowed anti-zionists so it could go either way (Paris), and one of the main zionism-enforcing and free speech-suppressing cities of the world (London)
Dublin's gonna be a great time for everyone involved, and the other two are probably going to further the cause by generating the right headlines.