I think the point been made is that on one hand you have Israel jusifying heavy loss of life in the name of anti terrorism whilst at the same time celerbrating an act of terrorism by their own right wing element.............. in this case against the British.
One man's freedom fighter is another man's terrorist.
I get your point Dom about Blair and his hypocrisy but as to the celebrations themselves, it's a matter for the Israeli conscience and to be honest they won't care what the rest of the world thinks on way or the other.
I believe that Zionists were the first people actually called terrorists in the modern sense: before that the term was mostly applied to people like the French revolutionaries, who instituted a reign of terror but did so as the government. The modern meaning implies pressure groups using terror to force the hand of governments.