I am often a critic of Tesla but it is simply silly to conflate one or even a handful of such cases to mean anything more than what is very likely a simple one-off manufacturing defect - but it is also a situation where Tesla should have willingly covered it under warranty if for no reason other than to kill it becoming a story.
I certainly would not chose to avoid buying a Tesla or any other EV based on this - heck nearly all petrol vehicles would have died (and often do) in much less water.
Anyone making a decision based on this story was biased from the start is simply looking for confirmation of their bias.