That's certainly not what happened. Where did that theory come from?

. Ffs, Müller-Wohlfahrt has been in charge at Bayern for almost 40 years and for the German nationalteam for almost 20 years. He successfully treated serious injuries for athletes from all over the world, including for example Kobe Bryant and Usain Bolt. He's sometimes too careful in regards to his players and some of the tension between him and Guardiola was built on him not allowing players to be rushed back to play. He's a bit of an odd character and some of his methods might be dubious or even a bit shady, but he's not some weird alternative doctor who doesn't use regular medicine, technologies, techniques at all.
I guess, he just adds a bit of mumbo-jumbo because many superstar athletes are a bit supersticious and probably love that he does something unique around the important foundamental medical stuff. It's why he became a bit of a star himself and he clearly enjoys that image. It doesn't mean he's delusional and treats serious injuries solely with honey.