You're correct about the engine issue. In the past, when it was my hobby to modify cars, the only real issue you had was to make sure that the new engine met the emissions standards for the year and make of car, and the state you lived in. And while it's a good idea to keep those numbers together, you won't automatically be suspected if you don't, it just places more of the burden of proof on you.
But back to the MS issue. What I'm saying is that while MS, when pushed, will admit that all these conditions mean is that you should obey the software license, the fact is that the way they word the issue (or the way their lawyers do), is specifically intended to cause confusion and doubt about accepting a legal donation of a computer without a Microsoft operating system.
The issue about Naked PC's came up a year or so ago, when MS decided to offer incentives to OEM's who informed MS about customers who bought PC's without operating systems. MS's stated reason for this was that they were concerned about customers who were confused about volume licensing issues, but all in all, it made them look pretty silly, and they had to back away from it a bit. They still raise this issue in their FAQ about volume licenses though.
I don't have a fundamental problem with MS, or with their software, which I mostly like (I wouldn't be visiting a site called WinCustomize if I were that much against Windows). The problem I have with them, and others, like the RIAA, etc., is the standard presumption on their part that their customers are thieves and scoundrels unless proven otherwise, and apparently, no level of proof seems to be enough.
Sooner or later, the customers will realize what low regard they are held in by these companies, and that behaviour will backfire on the companies. It is a poor business plan that will fail at some point.