I don't think Valve is being unethical in protecting their games. They're not controlling their products because "fuck you consumers, we are evil and wish to suppress your rights", they're doing it (at least I presume) because if they didn't, no one would buy their games and they wouldn't be able to operate. A food vendor can't make a similar claim (well, at least not in as strong a way -- though I guess there are things like secret recipes) to justify hiding things from consumers.
1) Custom software development (i.e bespoke client work) and 2) Crowdsourcing
The custom software argument seems odd, even though the main user (the client) would get the source code and freedom in that instance not only does it promote keeping software locked away as trade secrets, in most cases the actual end users will not get freedom with the software it will really just be senior management.
It's a black box so to speak. Someone else pointed out the food comparison, it would in fact be unethical to sell someone food without telling them how it was produced and what was in it, and I think that's a reasonable take on the software situation.
However, one could argue that the GPL makes it almost impossible to build a traditional software sales business if the product is GPL licensed. The first person who buys it gains a legal exception to copyright to give it out freely, but that happens whether its GPL licensed or proprietary, we just call it piracy in the latter case.
So in some respect they're working against the idea of traditional software sales as a side effect of upholding the freedoms they promote.
Extending the analogy to software, if your program accesses personal information, contacts remote servers, inserts itself into the kernel, etc. then you have an ethical obligation to publish that behavior. But there's no ethical obligation to provide the source code, and indeed, providing the source code wouldn't be sufficient to satisfy your other obligations (because it wouldn't be accessible to 99% of users).
If that means someone else can come along and reproduce it, tough.
At the core of food are plants that have a set of easily copiable and modifiable DNA. Apparently, biotech corps think that they have DRM on plants.
http://en.wikipedia.org/wiki/Monsanto_Canada_Inc._v._Schmeis...