I don't know, I don't know who the witnesses against him are, so I am refraining from making assumptions about their credibility.
Well, at the very least a few suspicious tests have come up. Not enough to charge him with a positive test. Personally I don't think passing tests mean very much. Lots of people have passed lots of tests while doing lots of drugs.
They are not only going after him. They have named four other people as well. These people are either recently or currently active in cycling as team managers/consultants/doctors.
While I agree it does not make much sense for Lance to cheat, especially in his comeback, when you apply a rational plus/minus calculation to it, I do believe that he is very arrogant. We have seen other athletes show an extraordinary amount of arrogance in similar situations (Bonds, Clemons, Palmeiro, Jones), so I don't think that is a heavy factor one way or the other.
Just to be clear, USADA cannot ban him from Triathlon. Triathlon, both WTC and ITU, are signatories to the WADA code. Their athletes sign, as a condition of participation, acknowledgments that allow such provisional suspensions. WTC, as a signatory to the WADA code, is obligated to suspend in such circumstances. Other sports, such as NFL, which choose not to sign the WADA code can design their own testing protocols, rights guarantees and procedures, and penalties.