Pouring water on lithium-ion battery fires is not only safe it’s the primary means of fighting them. It does not make them explode a second time, what it does do is cool down the battery.
Lithium battery fires though, there you’ll want a class D extinguisher. Those batteries aren’t in EVs though.
Double negatives affirming one another instead of negating is a common thing in language, known as “emphatic negation” or “negative concord”. Middle English used emphatic negation and various English dialects still use it to this day including African-American English. They’re saying exactly what they mean, just not in Standard English. Just like they’re probably not pronouncing the words the same way. No reason to get annoyed.