Doping

I thought that was the angle they were going for with him

The angle is fraud. He represented his value as a promotional tool as something other than what it was, by claiming to win clean when really he was doped up to the eyeballs. The opinions cited above go to two questions which have to be proven by Landis et al in order to get a judgement against him

1. Being clean was a material consideration for USPS when they decided to continue sponsoring Armstrong
   
2. USPS suffered a loss as a result of the false claim, i.e. the benefit of sponsorship was less than what they paid.
   
   

It's not enough just to prove that Armstrong is a lying scumbag, otherwise the case would have been over by now, they have to prove that his lies caused USPS to hand over money which they wouldn't have if they had known he was a lying scumbag, and that they suffered a material loss as a result.