It's not proof, it casts doubt due to its unusualness.TBH I think you read it how you want to. Loads of other folk on here are making the same jokes, how do you read them?
Bolt jogged the last 10 metres of the 100metres final. People don't like that. He was showboating out of the sheer shock that nobody was anywhere near him. Using that as proof he is doping is a bit of a weak argument.
Never seen showboating in an Olympic 100m final before, that casts enough doubt of itself.