I doubt it, but even if that were the case it would not support your earlier claim. When fermenting things you will generally intentionally introduce a very small quantity of a carefully controlled culture to the bulk media. Which is to say, you would almost certainly have your own yeast culture at home that you would inoculate the mead-to-be with. Maintaining a sourdough start is an example of this practice.
If you want to start your own culture from scratch there are established practices for culturing "wild" yeast from the environment.
It's absolutely why its done, because people would otherwise inadvertently initiate fermentation with it.
Not seeing this and instead going for 'hehe my little dude, pasteurisation doesn't destroy the sugar, you can still add yeast and ferment it' doesn't come across as particularly impressive from my perspective.
I never said that? It's well known that heat alters honey.
Obviously the purpose of pasteurization is either preservation or food safety (but I repeat myself) as opposed to preventing people from making mead. I claim no particular knowledge of which specific microorganisms are primarily responsible for the spoilage that might otherwise occur, nor the precise consequences of such spoilage.
If you want to start your own culture from scratch there are established practices for culturing "wild" yeast from the environment.