Over the last 6 or so years, we have personally run an oil with moly in it and NOT had 'any' clutch slippage on various bikes including a Honda XR80, XR100, XR200, XR250, three different XR650R's, two different CR250R's, CRF450R, a TR200 FatCat, two different Yamaha WR426F's, IT490, YZ400, MX250A a Kawasaki KX250, and I'm probably leaving a few out!
I don't believe moly in and of itself is bad for wet clutches, but the type and amount of moly used can pose problems. You're looking for trouble if you use an oil that contains larger sizes of moly powder solids or has a high concentration of moly (whether solid MoS2 or soluble moly such as MoDTC). An oil that's properly additized with moly can be safe for wet clutches. Schaeffer's Micron Moly Racing oil is just one example.