The iPhone, by contrast, has millions upon millions of reasons you might need/want to tinker with the software. Hence the demand for source. Seriously, RMS is not the one with a logic problem.
Unfortunately, the line between the two is blurry at best. For example, I'm not sure how well this jives with the case of the printer software which provided the catalyst for RMS starting the FS movement in the first place.
See for example, "Predictable Programs in Barcodes":
From the abstract: "...In particular, we consider programs for microwave ovens, which provide a basic open API for controlling cooking times..."
The authors were only able to _simulate_ a microwave oven, presumably because the software on real microwave ovens is closed. A reasonable argument could be made that the proprietary nature of microwave oven software has limited innovation in this market.
The point is not that the iPhone should be considered the same as a microwave, but that there is no hard line. If you are going to be a fundamentalist, like RMS, you need to carry it through to all things. There is no point where a microwave becomes definably different than an iPhone. Its a continuum.
"The only way I could justify this is if I began developing a free replacement for that very program. It is ok to use a nonfree program for the purpose of developing its free replacement." - RMS answering 22.
When you buy a microwave, you are buying it to heat food. You are not expecting to be able to browse the web on it or play games. If you are, then you need your head examined or to invent this new product (if you are right that it's a reasonable/desirable expectation, there should be a market for it). I think the distinction is actually very very clear, continuum or not.
Once the microwave starts allowing for remote control and twittering its status, the line does become more blurred ;)
iPod classic, it's not going to hurt anyone if you screw with the firmware, you should be free to tinker to your heart's content. There are also enough obvious deficiencies (lack of support for a variety of codecs) which can be improved.
Same with a TV, the Kindle, the Drobo.
However, no one is clamoring to write apps for a microwave. A microwave really just has one function and as long as it does that one thing then it doesn't really matter how the software works.
To a hardware hacker that would be a false statement.
Tinkering with the software on your phone has much less potential to do so, for me it's simple if it has software in it and you bought it then you should be able to tinker with it.