no excuse imo. its a car. Its even stupider that it failed from rain (even bad rain) in a car park. Cars can deal with 1m water easily (most batteries are that high, the air intake for the engine is easily that high (I will ignore Lambos and similar, built for different purposes).
In the worst case for a ‘normal’ car (what is the TLA for them now?) a replacement battery would cost you a couple hundred bucks at most.
Even if water got into the intake, the whole overhaul would not cost $20k or whatever it was.