Because it has opt-out search collaboration with Amazon. When an operating system is free, the money has to come from somewhere...
He's consistent in his principles and likes parrots, I am amused (and he's right about the parrots, seriously, don't get pets if you don't want to keep them for the long haul). I don't really agree with his priorities with regards to software, but I would prefer if it were opt-in (like Debian's popularity contest thing, iirc?) instead of opt-out.
Firefox has been funded for years with money from basically the same thing with Google. Did Stallman object to that?
Say what you will about Stallman, but the dude is pretty consistent in objecting to things. For my part, I think that the list of problems in the world that can be attributed to people advocating too forcefully and uncompromisingly for good ideas is pretty small, so I applaud him even when I might be inclined to say "enh, not such a big deal in this case" personally. As for this particular case, I will say that it's qualitatively different from the Firefox case. With Firefox, you're searching the web, so there's an inherent expectation that a third-party is involved. With this, you're searching your computer by intention, and sending it off to a third-party is unnecessary and a bit weird. This is basically the equivalent of intercepting the stuff you type into Win7's start menu -- does Canonical really need to know how often you type "excel" or "2013 budget" or whatever? No, they don't. And is the benefit to me worth it? Well, since the "benefit" is me seeing ads from Amazon that are essentially guaranteed to be irrelevant to me (number of times I have tried to open a program or document and been interested in buying a related product: ZERO), heck no. It's a dumb thing for Canonical to have done, whether or not you think it's a major privacy violation. Fortunately you can disable it (or just use GNOME 3, which is vastly better than Unity anyway), but it's definitely something worth calling out as a breach of user trust.
That rider is there because idiots probably do buy him parrots. Think about what the demographic of "people who invite Richard Stallman to speak" consists of.
Given it will be obvious from the first time you search what's going on I think extending the definition of "spyware" to cover this case is trying a bit hard. Spyware does things without your knowledge.
I'm not really seeing the issue, but then again I've worked for web marketing companies before. I'm under no illusion that anything you do at any point isn't either tracked or going to be tracked. In the current age, all people want to know is what drives consumption, and how to more effectively direct consumption. I'm not going to knock the company that's been doing more for Linux on the Desktop than anyone else in a freaking decade trying to fund their efforts.