I think there is a distinction to draw there between stochasticity in the use and in the evolution of language (which is not clean as they are not independent). The language evolves stochastically, as it does so by being used in exchanges. But the use could be deterministic with the exchanges being random and the function of update based on exchange. I still think there is stochasticity in the use itself, I choose my words, go back and delete and rewrite, explain again in a different way when the audience looks at me unimpressed etc. I just don’t see fluidity as a proof of stochasticity of evolution or the other way around and in fact think the interaction is a quite interesting domain.