It seems to me that Cobb isn't selling Denso ROMs, they're selling modifications to those ROMs. Those modifications are wrapped in Denso ROM images for the sake of usability, and since Cobb's customers already have rights to the rest of the ROM image (the rights come with the car) I don't see a problem.
If Denso ever gets upset about copies of their ROMs changing hands, then Cobb just has to tweak their delivery process to send diffs rather than complete images. That would provide exactly the same value to the customer, without distributing copies of Denso ROMs. (Actually, I wouldn't be surprised if they did it that way already, but I don't have an AP so I wouldn't know.)
What the NASIOC seller was doing is morally equivalent to downloading commercial songs off the internet and burning CDs from them. He even made that analogy himself.
Any time Cobb/EcuTek/whoever feels a need to explain why they and their tuners are concerned about open source projects, all they gotta do is link to that thread. It doesn't get much clearer:
I have a few cobb maps, not from reading/saving them, but from other members in the OS world. I DO NOT sell them for profit, and never will. I do however offer them to those in need, without charge, on occasion for people to use as a basemap, for tuning for example. If my friend asks me to burn him a CD, I will, just as the majority of people do.
What surprised me was that he thought that equivalance somehow made his actions more defensible, rather than less... kids these days, what can ya do.