He didn’t say he blamed the chaos on the Iraq war. He said he blamed the (current) Iraq war on the chaos there. You seem to have read that backwards.
As easy as it is to want to blame Obama, the truth is it was Bush who set the withdrawal timetable, and the elected government of Iraq didn’t want to extend it. The Shiites couldn’t wait to boot the Sunnis out of any power in the government, which is why the Sunni troops don’t consider fighting ISIS their battle. Both sides wanted us out so they could get back to killing each other.
Ironically, Joe Biden may have been right about something for the only time in his life when he suggested the only long term solution might be splitting Iraq into Sunni, Shiite and Kurdish states. OTOH, as long as Muslims are killing each other, we can hope they will be too busy to cause us trouble.
I considered that reading, which is closer to his words, but in context that really didn't make much sense.
What's going on there now is not a war exactly, chaos would be more accurate. The Iraq war ended when Iraq surrendered.
I think he just phrased it awkwardly. Watching the video, immediately after he says that he continues with "these are the people" and he's talking about it Cheney etc.
To me, it's clear that he's blaming the current chaos on the Iraq war Cheney supported.