^^The way Picard sees it, a lot of people behaved in unfortunate or out-of-character ways due to their terror in the Borg crisis (or at least what seemed like a major Borg crisis back in those innocent pre-Destiny days). So he decided not to hold it against them. Kadohata made poor decisions in the "mutiny," but so did Worf by forgetting his diplomatic training and acting like a berserker; so did Nechayev by forgetting the trust and respect she'd shared with Picard in the past; so did Picard himself by being so quick to act like a renegade rather than finding a more diplomatic solution. Basically it wasn't anybody's finest hour, and it would be unproductive to cast blame because there was plenty of blame to go around.
As for Leybenzon and T'Lana, they weren't punished for their actions. Picard was just as willing to forgive them, even though they, unlike Kadohata, didn't change their minds about siding with the admiralty over Picard. After all, they all sincerely believed they were acting in the best interests of the Federation, they just disagreed on how to do that. But T'Lana recognized that her behavior revealed problems she needed a leave of absence to work out; and Leybenzon made a good-faith effort to work with the rest of the crew for a few months, but decided he couldn't trust Picard when another Borg-related mission arose.
Just in general, blame and recriminations don't do much good. They're not a way of solving problems, just perpetuating them. It's better to be able to put past disagreements behind you and work together. Just ask Barack Obama and Hillary Clinton.
As for Leybenzon and T'Lana, they weren't punished for their actions. Picard was just as willing to forgive them, even though they, unlike Kadohata, didn't change their minds about siding with the admiralty over Picard. After all, they all sincerely believed they were acting in the best interests of the Federation, they just disagreed on how to do that. But T'Lana recognized that her behavior revealed problems she needed a leave of absence to work out; and Leybenzon made a good-faith effort to work with the rest of the crew for a few months, but decided he couldn't trust Picard when another Borg-related mission arose.
Just in general, blame and recriminations don't do much good. They're not a way of solving problems, just perpetuating them. It's better to be able to put past disagreements behind you and work together. Just ask Barack Obama and Hillary Clinton.