Whenever a drivers action on a road is sudden, it is due to one of 2 things. Something unexpected (animal or child darting into the road, something falling on the road. ice patch, blowout, etc...) or driver inattention (on phone, fiddling with controls, taking eyes off road, etc...)
Of course these articles often don't contain the finer details so we are left with conjecture and speculation.
As mentioned, a fairly straight road with good sight lines. Middle of the afternoon. Based on the article, this likely lands in the hands of the driver.