Eight weeks as a rule of thumb for mead? I've never heard that before. That is a very short time period for something to finish fermenting and be completely clear. That has not been close to my experience at all.
And campden doesn't "neuter" yeast- it's an antioxidant and preservative. Wine yeast is amazingly tolerant of sulfites- that's why winemakers routinely use them. And even if it did kill yeast (and it doesn't), it wouldn't clear the mead any faster anyway. Things in suspension don't have to be actively alive to cloud a mead- protein particles, pectin haze, starch, etc, all can cause haze and cloudiness in a mead. It's rare for it to be a yeast haze, although that can happen. But even if it's a yeast haze, campden is not an effective clearing agent.