Satirical? I wish. I'm afraid that Ray Comfort and Kirk Cameron were quite sincere about their banana proof for the existence of God. Did they appear a little silly? Yes, but silliness is not the same as satire. To conclude that their argument was satirical would mean that they were actually ridiculing belief in God, which they were not. Comfort is an evangelist minister who writes Christian books and is known for his proclivity (if not ability) for debating the existence of God against atheists.
Now, if you meant that the banana caper could be easily satirized, then you are right. In fact, it has been on numerous occasions. Just do a search for "banana" and "God" on YouTube, and you'll find all sorts of banana satires.