The chemical secrets that help keep honey fresh for so long

They don't mention it specifically, but I thought osmosis was the primary mechanism. Water flows towards dissolved solutes, and honey has tons of solute and little water, so water will flow out of bacteria into the honey until an equilibrium is reached. Bacteria can't survive that level of dessication.

Then if you want to make mead, the first thing you have to do is add a bunch of water so bacteria can grow.