Why?
It's totally plausible.
As a former art teacher, I gave 100% to a student that did a hole, the theme was to express their feeling. Every criteria was respected. It had generated a huge debate in the class!!
I often encouraged student to think out of the box. If it's the philosophy teachers goal as well, he should reward that student. Nevertheless, usually there is a criteria for the number of words, and the student should be penalised for that.
As a student, I did draw an 1000 words essay, since one image is worth a thousand word. I got an F.
To say that students are doing bold things, teacher are grading in personal ways. It would be surprising it never happened (not necessarily the 'why' question, but similar.)

Mexican Seafood is a Nirvana song. Maybe this is what Mr. Seafood was referencing?