I agree.. finding an image on google does not automatically grant a licence to use.
However...don't you think Zaks work would be considered a derivative work under US Copyright Office Circular 14 : Derivative Works?
Where:To be copyrightable, a derivative work must be different enough from the original to be regarded as a "new work"
I think so...I am not a lawyer but I reckon Zak created a new work..