How windy was it that day? Mechanical turbulence is caused by smooth air hitting things on the ground (buildings / hills / trees etc.)... Maybe it was a gust?
I'm pretty the confident the E75 pilot would have aimed for a touch-down point
after where the DC-10 touched-down (i.e., higher than the vortices), and that ATC had provided sufficient spacing between the heavy and the E75.
My 2c as a private pilot