Nope, raising the humidity helps to loosen up the mucus so it is easier to expel(like a humidifier or nebulizer for a child when they have pneumonia). Snakes don't have a diaphragm like we do, and are unable to cough. If the mucus dries up, it gets sticky, which makes the lungs unable to expand so they can breathe. When this decreased lung capacity occurs, the snake has to breathe more rapidly to get enough oxygen. If the infection is severe enough, the snake will eventually suffocate from the constricting, dried mucus.

60-70% is plenty, 65% should be sufficient enough to do its job. If he's not using his hides, make sure they're small enough. Also, if he's roaming his tub constantly, you can fill it to the top with loosly crumpled newspaper so he can settle down.