So, it was Guardian's spin on his words "I agree with the president", not exactly Ronaldo comparing his position to slavery.
I saw integral versions of both those interviews that summer, with Blatter and with Ronaldo (the latter held in Portuguese, I also read a transcript of an English translation).
In a 30 mins long TV interview, among other things, Blatter spoke about contracts, transfers, licences, fees, agents, etc. One of the early questions in the interview was about Ronaldo possibly asking for a move that summer - Blatter answered that in his opinion no one should be held at any club against one's will. That was the only moment during the interview when Ronaldo was mentioned. Some 15 minutes and 5 or 6 questions later, none of which had anything to do with Ronaldo, replying to a question about current regulations, Blatter said that there were examples akin to slavery in contemporary football.
It was the way Sky Sports cut the interview and the media spun it (linked Guardian article is a good example) which created an impression that he spoke about Ronaldo when he said that.
Ronaldo's interview was held in the street, in front of the hospital building he had just left (he was ambushed there by a RTP crew). He spoke mainly about the injury (it was 2 days after the operation and he was on crutches) and was obviously annoyed with questions about the transfer, including those on Blatter. Yes, I'd agree it could had been deliberately timed by his representatives and coordinated with Blatter's interview - and he definitely looked like he wanted to leave - but my impression was that he didn't know what Blatter had exactly said, never listened carefully to the journalist, just said 'I agree with the president'. (It looked more like agreeing on his general view on the player v club issue.)
Re Blatter - and I said something similar in the newbie forum at the time - blinded by his disgraceful 'slavery' comment, everyone seemed to have overlooked another shameful fact back then: that Fifa president actually had taken part (and sides) in the ongoing transfer war between two clubs.
Edit - no need to thank me for bringing back these nostalgic memories of that unforgettable summer.