Again you're forgetting two things, he WASN'T punished for refusing to play, because Mancini made this claim, alienated Tevez, and the investigation concluded he DIDN'T refuse to come on the pitch, Mancinin, getting spanked by Bayern, taking off a striker because he wanted to hopefully not concede more, then did want to bring on a striker for the end. Tevez, having ALREADY WARMED UP, said he didn't need to warm up and Mancini, in a bad mood, being a bad translator, threw a strop after already having a go at Dzeko and I think IIRC, then had a go at Zabaleta.
Mancini created the situation by acting like a petulant child and literally lying on camera about the incident to deflect from a pretty woeful performance against Bayern....... the rest is history. Mancini alienated Tevez, Mancini said Tevez would never play for them again. Then again IIRC after the investigation and Mancini was pretty much proven a twit, he left the door open for Tevez to return, who at that point didn't give a monkeys (and would you if your manager lied about you and caused a club investigation over things that never happened......just because he was in a bad mood?) smegged off and didn't bother to turn up to training(not his best move) at which point Mancini again slammed the door shut with maybe more justification. But did Tevez fail to show up to training before Mancini lied and stuck him in the reserves and treated him like crap for a month, no.
Mancini got it wrong, Mancini devalued the transfer fee they could get with Tevez.
Think about it, he could have said nothing, kept it entirely private and let Tevez leave in the transfer window with no "official" problems..... you think they can get the same transfer fee now? The wage he's on he's getting around a million a month........ delayed and refusing offers is vindictive and stupid, not smart.