I don't know Greg so I can't comment on his character, I don't know Lance, so I can't comment on his either, but I can comment on the actions that I see, just like everyone else, and from the actions:
I see Lance vehemently denying the accusations and as being one of the most tested riders in the world and never coming up short, and Lemond firing off his accusations right in the middle of the Tour with no hard evidence other than recountings of conversations and his recollections.
I could say things about Lance like; the pressure for in the Tour is IMMENSE and would drive a hard charging competitor to do questionable things sometimes.., and about Lemond, here is a public figure, why would he destroy the rest of his fame and credibility over completely false accusations...
But such philosophizing serves no purpose other then to whip up more speculation...
The one thing that I think applies to situation though is that relationship axiom that when person A says something negative about person B you learn far more about person A than about person B...
Have a good one!
Feanor