They didn't sue him, yes. But they did specifically mention DMCA, and that they believe what he did to be illegal. So, at the very least, it was an implied threat. Which he ignored because "
if we lived in the US we would have been in breach of the DMCA".
I also don't see anything in that comment saying that they should be forced to decouple software from hardware. What it says is that they shouldn't be allowed to legally prohibit their users from doing said decoupling on their own, if they have the resources and the expertise to do so.
Now, this position does result in their business model being non-viable - if working around such technical restrictions is not illegal, and it's cheaper than not doing so, then there will be a market in workarounds. But I think that is fair - there's no inherent right for some arbitrary business model to be viable, so the market sorts it out. Companies can still try to make it work by utilizing more sophisticated protective schemes that require more effort to break, raising the cost of such workarounds. But if it doesn't work for them, well, they will have to look for a different business model - sell the device at a higher price, say, to mitigate losses from savvy customers that cannot be milked; or rent it out instead of selling.
As to patents and copyrights - these are, indeed, legal tools that enable specific business models. They exist because we as a society (i.e. majority consensus) believe that these are necessary to stimulate creation of certain goods that would otherwise not be created at all - so we have established them as a kind of explicit social contract. One could argue that their present form (terms, especially, and domain of applicability) is not actually agreed upon by the majority; but I think most people agree with the basic principle. They also have some important exemptions, such as fair use, which are also there to ensure a balance between keeping the business model viable, and protecting other social interests.
I don't think that a similar consensus exists with respect to DMCA protections. If you take a random person off the street, and explain them a situation that DMCA makes illegal, as the original post in this thread, the most common reaction is "WTF? This is insane". And I think it's for a good reason - DMCA doesn't really enable any business models that are uniquely suited to producing goods and services that the society needs, and that cannot be produced through any other business model. All it does is provide some opportunity for extra profit. I don't think that most people would consider extra profit for a few businesses to be sufficient justification for very heavy-handed legal restrictions that defy common sense.