I really don't think so. The person he's responding to said "I have no confidence in the clean generation" and "there is no longer anything to see here". Walsh is trying to convince this person that the peloton is cleaner.
I think the implication of those tweets is actually that Contador is clean now, the evidence being that his performances in flatt TTs are worse post-ban than they were previously. He is trying to convince someone that the peloton has cleaned up.
Actually I can kind of picture this.
Other teams: Hey Belkin! Attacking a guy when he's had a puncture? Not cool.
Belkin: Nah it's OK because ... uh ... Puerto?