Jordan, Malone, Bird and Kareem would state to the contrary. They were all hyper-productive even beyond age 27.
Lebron will have played damn near 30,000 minutes in the league after this season. Kobe, who's been playing seven more seasons, is at 41,000 minutes played.
Because the trends Lebron set in the regular season are completely antithetical to his trends in the playoffs. You're still arguing on the hypothetical that Lebron's coin-flips will stop landing tails and hit heads sometime in the near future. You need to stop ignoring the human element in all of this.
EDIT: I just noticed you are wrong about Jordan at age 27. He had already won a ring by that time, too. In fact, he didn't turn 28 until February 17 '92, which means he was on his way to a repeat.
Jordan part, didn't check so you might be right.
On the coin flips. Yes they will even out. I don't even see how this is debatable considering, well, they've already evened out! His playoff stats vs his regular season stats are basically the same. Same for Jordan when I checked. You were cherry picking games that showed he played below average. But you know what, that's what an average is. If you usually score 25 and get 10, that doesn't mean you'll get 20 and 10 a game. It means that you're probably getting an equal amount of 30 and 15 and 20 and 5 games. So to say that he has performed below his regular season stats is wrong. He hasn't. Yeah, you can cherry pick his games that bring his average down, but you could do that for any player.
What I'm saying is that its probable that he will end up having some great finals series.
On Jordan, Malone, Bird...Well, yeah. They were in their prime. That's exactly what I'm saying. And Kobe, while he has regressed a bit this year, is still producing at a pretty high level. I don't see how that's an argument against using age.
tl;dr Adam Morrison is the GOAT
Edit: Also, are you faulting LeBron for taking that Cavs team to the finals and then having a bad series? Becuase taking that team there in the first place, more or less on his own, was incredible.