I like character conflict and dilemma, I'm not asking for it to be toned down. I don't think it should've been a dilemma for Kadohata because I think she should've sided with Picard from the jump. What's the point of making a big deal about her being previously on the ENT-D if she balks at backing him on something so critical, so personal to him?
That's too simplistic. Kadohata isn't solely a member of the Enterprise crew, she's a member of Starfleet. She swore her allegiance to Starfleet. She values what it represents and she's loyal to its chain of command. She spent four years in the Academy training to develop that loyalty. She was loyal to Starfleet for years before she ever met Jean-Luc Picard.
The whole point of this situation was that it was a dilemma for the crew. It wasn't "us vs. them." Nechayev and Jellico weren't the enemy, they were fellow members of Starfleet. The crew was facing a situation where their loyalty was divided, where they had to choose between two sides that both deserved their allegiance and both had good arguments on their side. That shouldn't be a pat, simple choice for any Starfleet officer to make. Picard wrestled with his own conscience before choosing to defy the superiors he'd sworn his loyalty to. It would be illogical to expect any other Enterprise crewmembers to be any less divided, and it would be illogical to expect them all to come down on the same side, or to side against Picard only if they had personal failings of some sort. This wasn't just a situation about personal loyalty or tribal allegiance. Their own organization was divided and there was no obvious right or wrong path to take. It's perfectly plausible that different crewmembers with equally good intentions and equal loyalty to Picard would still end up on different sides of the decision.
In "First Contact" he had shown that he knew the Borg like no other, until Janeway/Voyager crew returned, and that he had been right. He had also proven himself in "Insurrection", etc. Now, those two examples happened on the E, but I'm guessing Kadohata kept in touch with the crew during that time at least a little bit.
And how many crises did Admirals Nechayev and Jellico save the Federation from? How many decisions have they made over their careers that were equally right? Sure, Jellico hasn't always been portrayed as the nicest guy (at least not in Peter David's fiction), but he couldn't have gotten where he is without earning it. Nechayev and Jellico may have earned Kadohata's loyalty just as legitimately as Picard did. She may not have served on the same starship with them, but they're part of the same organization, the same family. At the very least, she's been conditioned throughout her whole career to respect the rank, to respect the chain of command. However much personal respect she had for Picard, he was the one committing mutiny, the one engaged in overtly criminal behavior. That's not something you just casually go along with.
Don't forget we're talking about an essentially military organization. The training is to obey even when you disagree. You can debate, you can protest, but when an order comes down, you follow it whether you like it or not. Miranda followed legitimate orders from her superiors, orders which Picard had defied. However noble Picard's ends were, his means were illegal. And that meant Miranda had a duty to arrest him. It's not just about personal feelings.
Besides, we know in retrospect that Picard was right, but she couldn't know that at the time. It's easy to be a Monday morning quarterback, but she didn't have the luxury of that kind of certainty. There was no clear, good solution, just a choice between two insane, desperate plans. If anything, Picard's plan was the more insane and desperate one, since he had no reason to believe that reactivating the Doomsday Machine could actually work.
In the Star Trek world, we've seen time and again how the crew will break the rules to back a friend. The TOS crew was notorious for it.
That's a false caricature. Spock did it in "The Menagerie," Kirk did it in "Amok Time" and The Search for Spock, McCoy did it in "The Empath," and that's about it. Four times. The rest of the time, they followed the chain of command even when they didn't like it. In "The Galileo Seven," Kirk followed a (silly) standing order to observe a scientific phenomenon even though he was on an urgent mission to deliver medicines, and later he reluctantly but obediently followed Commissioner Ferris's order to abandon his crewmembers. He did all he could to bend the letter of the orders, but he still would have left Spock and McCoy to die because it was what he was ordered to do.
If they didn't follow their orders most of the time, they would've been thrown out of the service or into the brig before very long at all. It's totally wrong, and totally unfair to the characters, to reduce them to renegades who routinely betray their oaths and their responsibilities to the greater organization for the sake of personal feelings.
I think it did a disservice to Kadohata's character, or my estimation of her, to have her go against Picard. But then, she couldn't even maintain that and she backtracked again.
I think it would've done her a greater disservice to portray her as someone who would casually betray her solemn oath to Starfleet.