I don't think that nuance is lost on anyone. But does it succeed? That's debatable. After all, in order to make the point that "making fun of native Americans is bad", the show still ends up making fun of native Americans. Making fun of native Americans might be "bad," but hey it's hilarious, just another one of Jerry's silly hijinks, so how bad could it really be?
Additionally Winona comes off as an oversensitive snowflake when she accuses Jerry of lowkey calling her an "Indian giver." In other words, maybe Jerry's a little racist, and that's wrong and silly, but being sensitive about it is equally wrong and silly, is the message. Fortunately Winona breaks it off and the show can go back to forgetting Native Americans exist as anything but a foil to Jerry's gang.
Furthermore, because real-life Jerry is so "brave" as to skewer character-Jerry's racism, real-life Jerry gets to congratulate himself for being woke.
To sum up, Jerry Seinfeld scores points for himself at the expense of native Americans, is one way to interpret what happened.
Seinfeld himself has conceded that the episode didn't age well, so whether or not you agree with parent poster, it's not like he's really being so "odd" and out-there in his reasoning.
> the show still ends up making fun of native Americans.
I disagree that it does.
Also in the link you've provided Seinfeld only says "You could never do that today". You've interpreted that as him conceding that the episode didn't age well. That's a stretch. (To be fair, the title of the article suggests he's admitting it's offensive but there doesn't seem to be anything to back that up).
One is pro-racism, and the other is anti-racism.
This show portays being racist as something stupid and worthy of ridicule.