That whole Shinken/Gosei battle part in that episode is actualy an explanation of the Gokaiger's cameo in the Gosei/Shinken movie. There they showed up and used DekaRanger to Go-Onger's Red keys. I think the time travel was a neat way to take a cameo that previously made no sense (seeing as the movie has to be before the Legend War, therefore the Ranger keys shoudn't exist yet) and make it work. It's also explains why a certain prominent extra hero never got a Ranger Key. It' pretty much an episode dedicated to a couple of continuity fixes.

It's weird that a show so disregarding of continuity dedicates a whole episode to fixing continuity errors.

Why? So them not doing the standard "we'll fix him with love" that Sentai does for nearly every other good-guy turned bad from Dragon Ranger to Gosei Knight makes it a let-down? I was impressed that they actually kept Sid and Barizorg from beginning to end because it was something not usually done in Sentai, it felt far more like a classic Sentai plot point then a modern one which made the fact it was revealed in the Liveman tribute even better.

Agreed. Besides, Barizorg was a cyborg that had to be built to keep Sid alive. As the Liveman tribute episode said, they said outright that if they tried to turn him back to human it may not work and kill Sid. It could have worked, but the odds were 50 50 in every sense of the definition. Keeping him evil and a cyborg was a great call, as it IMO made their relationship more dramatic and fun to watch.

No, because it means there is no purpose to Joe's story beyond forcing him to have a tenuous connection to the war.
I know you think the Zangyack are some of the best villains, and that's fine. But Barizorg was a waste. They could've had Sid turn on his own accord. They could've had anything else, really.
It made Joe's story superfluous because they outright told the audience "Sid is never coming back," making any time spent to be a waste.

I don't care how they handled it. All I merely said was the story was going to be a disappointment, and it was. Don't shove words in my mouth to attempt to form a case.

I wasn't shoving words in your mouth. I was just asking why you thought that immediately made it a disappointment.

But no, I don't think not saving him and establishing they can't save him early made it a waste. Just because they can't save him doesn't mean it doesn't matter. That doesn't change what's happened to Sid and Joe and if anything, makes the whole thing worse for all characters and paints the Zangyack empire as far more evil. I wish more Sentai would keep brainwashed/turncoat characters evil, because it does make the show far less predictable.

I said the story was a disappointment after the line.
You stated a scenario that had nothing to do with my declarations. I didn't mention anything about redeeming him, bringing him over to the hero's side, or any of that sort beyond "It was going to be disappointing."
You were shoving words in my mouth since I never mentioned how I thought the story should play out once in my post, nor any issue with how they handled the common story in any other series.

I was saying it was immediately a disappointment because by changing a character to the point of completely reprogramming their mind, it makes them pointless. Joe's connection to Sid was gone because Sid didn't exist anymore. The was no purpose in following it since there was nowhere else it could go. It wasn't a Basco scenario of the character turning because they desired to. Sid was captured, tortured, and became a nobody beyond a generic general character.

You seem to approach it in a one sided manner.
Why can't a character be evil because they felt it was the right path? Why can't a character turn for their own goals?

Barizorg didn't have to turn good. Why couldn't it play as a counterpart to Basco's story arc? Not being reprogrammed to be evil, but simply choosing to be evil.
It would provide Joe with a greater depth in his decision to kill him, but by making him irreversibly brainwashed, there was nothing to it. Sid was gone. Joe knew Sid was gone. Some of Barizorg's taunts towards Joe was that Sid was gone. It honestly felt like this story just ended, rather than being resolved properly because everyone knew Barizorg wasn't going to change back.

But that is a completely different plot to what they were going for. They were painting the Zangyack as irredeemably evil and something you wanted to hate. Joe's quest to save Barizorg turned into wanting to avenge Sid's "death" and get vengeance against the Zangyack, which is something all the characters, except maybe Don because the destruction of his planet isn't touched upon, have on their side. I can understand a character being revealed to have chosen evil if that's what they left open from the start, but the very first episode of the arc had Barizorg have no idea who Sid was and for Warz Gill to explain he was transformed against his will. I can understand complaining that a story went in one direction rather then the other if there was ever a "story crossroads" where it could've gone one way or the other, but there wasn't.

And yeah, a counterpart to Basco for Joe would've been cool but also sort of redundant. Why re-step the exact same story?

Agreed.