Rubbish. The article explains quite adequately the (very simple) reasoning: Edgium sends your data to Microsoft, not to Google. That data is, nowadays, the only compelling reason for being in the browser business (not counting those Mozilla loons who do it for fun).
And the investment required to put your own UI skin on someone else's engine is piss-all compared to maintaining your own engine. This move probably let them shed a few developer salaries.