It is completely preposterous to claim that honey is sterile with effective preservative properties only when it is undiluted. It's gravity has nothing to do with it. A liquid sugar water solution (depending on the concentration of sugar to water) is relatively viscous and just as effective of a preservative if the water used to dilute it is also sterile.
When used for curing, much of the preservative power of sugar and salt comes from driving off the water... the main ingredient that supports life and in this case bacterial growth. IF there was any chance of bacteria taking off in diluted honey, the cause would be from the tainted water that you used to dilute it with, and also in this case, possibly starting with unsterile wort before the honey is even pitched.
Another detail, as you partly mentioned earlier, is osmotic pressure. Again, this is independent of gravity of the substance. The importance of osmosis for bacterial growth will be impeded regardless of the form of sugar or salt used. Basic scientific evidence that brines work just as well as staving off bacterial infections as dry cures do supports this.
Whether liquid or solid (brines, cures, rubs, pickling, etc.) sugar, salt, acids, and even fats have preservative properties to stave off bacteria. The gravity of these substances has nothing to do with their ability to effectively preserve. Further proof --> smoking is basically a gas from and it also has potent preservative properties! Look up gravlax, saurbraten, saurkraut, jerky, preserved lemons, pickles, salt cod... The list goes on. And foods that would have normally spoiled, without some amount of curing, will hold up just fine for quite some time without refrigeration... independent of the gravity of the sugar they relied on for the curing.
I mentioned earlier that the type of honey you use in brewing is important. Please don't assume that everyone's scenario is equivalent to your own, as a beekeeper (how convenient), who uses extremely raw homegrown honey with a bunch of particulate matter suspended inside the product.