Theo was sent off for diving as Feyenoord drew 1-1 at Milan to reach the round of 16 3-2 on aggregate.
Van Hooijdonk said on Ziggo Sport: “A battered Feyenoord, with so many injuries and 1-0 down after half a minute... Then suddenly that idiot Theo Hernández arrives to help us.
"An unprecedented result.
"It's fantastic. Also for the whole club. Nobody expected this in such a turbulent period. Nobody."