

The person doing the spraying knows it’s just a water pistol. The person being sprayed has just been exposed to an unknown liquid by an unknown person. Considering this is also how acid attacks work, it’s not really that cool of a thing to do to people.
Except that isn’t how the question was worded…
I bolded some words for emphasis here, the question is not whether he should but whether they think he has to. Important difference.