It doesn’t take a lack of understanding of the word to arrive at the guy’s conclusion. It just takes an autistic reading of the word “water”. Water WILL boil in those conditions. Just like we don’t say water “spontaneously” boils when heated up in a kettle even though it’s the exact same thing happening.

So in the abstract, the guy is correct. Though, there is also a bottle of water in the picture, and when discussing which specific water will boil, it’s a guessing game, hence “spontaneous”. “Spontaneous” totally works for discussing the water in the picture.