What can be asserted without evidence can also be dismissed without evidence.
As there's a well known consensus that some factor (e.g. saltwater caused maintenance issues in this particular case) tends to be a game-breaker, then it's perfectly reasonable to dismiss 'without a citation' ideas that encounter this factor if the idea has no mention/citation of how they're going to fix, avoid or tolerate this.
If there's a plausible-seeming way that the idea can work despite the obstacle, then by all means we can discuss if that way will be sufficient or not; but if the idea simply ignores major problems, then there's nothing to discuss.
