The guy is a total dipshit. My guess is that he had mold in that injection. Preserving sterility when handling mushrooms is very hard, and boiling will not suffice for controlling spore load, both for the spores from the mushroom and that of the various molds that exist naturally and unnaturally in our environment. To obtain proper sterility most items have to be run in an autoclave at 14psi for at least two hours.
It’s a common misunderstanding the mushrooms need darkness to grow. Many mushrooms need a normal light cycle, though high intensity light can slow their growth as it tends to dry growing substrates. I know this because I grow a range of gourmet mushrooms. Psilocybin containing mushrooms are no different, and in fact when they are starved of light they tend to grow very irregularly, or so I am told, and the fruits themselves do not properly mature.
Anyways, humanity continues to surprise.