I've seen a lot of shit regarding juicing in my days so I'm really torn on this whole situation. But, I do have some insight.
My practical side says this is a ridiculous conspiracy theory. As someone who played Lebron twice in HS he, while not the specimen he is now, made the average guy look pathetic. I'm a legit 6'3 and he just seemed like a man child (I'm two years older).
You have to remember that to get to the place he is you are talking about 0.01% physical and genetic specimen. There absolutely are going to be outliers in the massive sample size that is our population and that is generally what makes these athletes stand out. They are paid to eat the perfect combination of food, their entire life is about training and maximizing their superior genetics via workouts.
I find it highly unlikely that the guy has taken HGH for 12 years stopped, then decided to flaunt his weight loss in the off season with zero discretion. The guy is still MASSIVE. Those gaunt pictures from earlier do not even remotely resemble the Lebron you see in uniform. Occams razor tells me we are most likely just seeing a guy with a shit load of miles on his body struggling through a few nagging injuries.
Now here is the other side.
To think PEDs don't exist in pro sports might be extremely naive. Without going into too many details my HS football team crushed it during my period making the final 4 in states I believe twice. I know of at least 8 friends that were taking some form of steroid injection and we are talking 16-18 year olds. The trainers knew it too and everyone basically just turned a blind eye.
Most PEDs that pro athletes use are going to be oxygen enhancers that give them additional stamina and let them perform and train at a higher level without getting tired.
I went on to Play tennis at a D1 school. Practice was usually 4-6 hours a day and grueling (We're talkin about practice). We spent 2 hours with the physio staff doing yoga and a bunch of bullshit and two of our players would regularly get shots of "vitamins" that a lot of us thought was pretty strange. Coincidentally an inquiry was opened on the head coach 2 years after I left the school for EPO use and during the process he passed away from a heart attack.
Another anecdote is that my freshman year I was failing a math course. I was placed with an adviser and after class I would have to take the coursework to her office and work through it with her. For tests I would skip the class and go directly to her office where we would take the test together. To be frank I had no fucking idea what I was doing and she would essentially walk me through step by step until I easily passed the test.
The point of all of this? I witnessed all of these things in a sport that makes little to no money for the university. I found it funny when people were shocked earlier this year when the story came out of athletes taking phantom classes for passing grades. BBall and Football are absolute cash cows, there is going to be cheating, there might be doping, and there definitely is going to be a lot of behind the scene bullshit taking place.
Bottom line, none of us can say if he or any of these guys are taking HGH. Is it possible? Sure. But, if Lebron is on something I can assure you that the vast majority of the league is, and it is a level playing field. This isn't something that a few lucky guys do to become stars, if its happening, it's prevalent.
The problem with drug testing is that the designers are always ahead of the test. If Lebron is on something it would likely be something we don't constantly hear about already.
My 2 cents, a bit of history, and some things I thought might be interesting.