I'm not at all sure what point or points you think I'm not addressing.
Some points about Terry you miss. (i) You assume he was fully match fit against Derby. Perhaps not. At the very least, he hadn't played any matches for several weeks. (ii) Why if he was fit to play but chose not to did Steve McLaren not mention this after the match? You would think McLaren would be pretty pissed off about it, wouldn't you? (iii) Who picks the team?
You keep saying it needs explaining. It is explained. He wasn't fit to play. It isn't a case of he was completely unfit on Wednesday and completely fit on Saturday. His level of fitness on Wednesday was judged not enough given the seriousness of the match. It is not in JT's character to opt out of a match, as you acknowledge. So why the silly conspiracy theory when the rational explanation stares you in the face?
You know, if this was a Liverpool player we were talking about, you wouldn't be suggesting this.