Probably because Crunchbase has Ben's title as "Co-founder & CTO", which is also what his LinkedIn says.
It's not unheard of for people who came on ex-post facto to be offered cofounder titles to sweeten the deal or for other reasons (titles are cheaper than equity, I suppose).
Edit: just rechecked and his LinkedIn notes Nov 2011 as the start date for Kaggle. Guess it was easier to condense it into one sentence than to explain the difference to TechCrunch's audience?
It's not unheard of for people who came on ex-post facto to be offered cofounder titles to sweeten the deal or for other reasons (titles are cheaper than equity, I suppose).
Edit: just rechecked and his LinkedIn notes Nov 2011 as the start date for Kaggle. Guess it was easier to condense it into one sentence than to explain the difference to TechCrunch's audience?