That stance is quint-essential Economist, based on my experience of reading them cover to cover - weekly - for the last 5 years.
They do have a free-market, lightly-regulated bias...but they are pragmatic when they need to be, and for that I love them.
Without getting into too much politics, people tend to forget how nuanced the 'Iraq War' decision was at the time. Obama has done a good job of summarizing it into a nice 'sound byte'. The war in Iraq is a "dumb war". The notion there that the outcome was so obvious that it shouldn't have been chosen. What many forget is that post-9/11, the intelligence community was indeed split. The UN SEC actually voted in favor of stricter sanctions and harsher actions against Saddam - if he didn't publicly state that he had no WMDs.
It's easy to say Bush knew there were no WMDs in Iraq and he was going there just for oil, but that's a cynical (and non-nuanced view) of the context of the time.
As Peter Bergen pointed out in his latest book Man Hunt, the decision for Obama to go to Abbottabad for Bin Laden was based on more circumstantial evidence than the decision for Bush to go to Iraq. Granted, the operations were different in scale - but that alone speaks to the fact that the decision to go to Iraq was supported by faulty intelligence.
Assuming that Bush had mal-intent and "knew" there were no WMD in Iraq - but was going just to avenge his father or w/e other story (disregarding everything else) is ridiculous at best.
One simple question I always pose to people when they make such statements about Iraq is...if Bush knew there were no WMDs in Iraq, why would he use that as a pretext when he would obviously be either right or wrong? It's not as if they can "plant" WMDs. It's either they will find it, or not. There is no middle ground.
So either he will be a hero, or he will be zero. He staked his entire presidency on that decision. He knew that when the presidency is done, he would just have his legacy. His entire legacy would be defined by that decision. There is no way, any rational president/person would make such a decision lightly and frivolously.
He would have been better off using the fact that Saddam has slaughtered hundreds of thousands of Kurds, or something else that is more 'ambiguous' that he can't REALLY be held accountable for.
Finding WMDs is a key tangible accountability metric.
So the fact The Economist was also a proponent of the Iraq War is just further proof as to the ambiguity in the intelligence community at the time of the decision - and how difficult such a decision was.