My opinion on this ("...they don't acknowledge this...")... I admit, I didn't read carefully about Exiftool (open source, freeware, whatever...) policy/disclaimer.
Still, even if Exiftool is *full* freeware, one who uses it, should make/write at least some credit to author. And as in this case (commercial, I believe), some donation wouldn't hurt, though.
Just my 2c -no need to comment :-)