While I would like to agree with you, and while you're responding to an argument that makes no sense, I think you need to work on those arguments a bit.
First, comparing artificially scarce goods to any kind of real scarce goods is something you should avoid doing at all. Arguments like spoilage aren't particularly relevant, and spoilage is usually (throughout the history of mankind) fought as much as possible. With the advent of preserves and freezing we can do a lot, but you still don't see the world overflowing with century old preserves; instead, variety increases and everyone can afford more fruit. Preventing spoilage means scarcity decreases.
With media it's the other way around. The more you prevent 'spoilage' in the form of piracy, the more scarcity you get. Fewer people can afford what they wish, and artificially scarce goods aren't as fungible as apples.
A more valid comparison would be to compare it to a non-scarce physical commodity like air; theoretically an industry could be constructed by forbidding everyone to breathe without a measuring mask. We could hand money paid for every breath to owners of oxygen producing woodland or other means of production. That would create a huge industry wherein people would feel the right to get paid, yet it's quite obvious that such an artificial scarcity would probably be harmful to humanity as a whole. Much like copyright can be considered harmful and arguments can be made that incremental improvements of art would be as productive even in its absence, although focus might be somewhat different.
And yes, economically piracy is a good thing, but not because of the somewhat flawed broken window fallacy, but because it is responsible for a large pareto improvement (the economic value of the gain made by those who obtain the product who would otherwise not have bought the product (ie, zero-loss for the producer)). Basically it reduces the deadweight loss damage caused by monopoly pricing and restores a modicum of competition when competition is illegal.
About the ethics; I consider monopoly rights inherently unethical and any upstanding citizen should ignore them if they can. There are a multitude of ways that we could promote work in the production of arts that would result in higher rates of production, better pay to (most, and in particularly to the specifically deserving, ie, artists and creators rather than lawyers or financiers) involved parties and without the damaging artificial scarcity.