Just the entire discussion of evolution and chicken/egg arguments.
Essentially, selection (whether it be natural, sexual, kin, or whatever, but not artificial) is a non-random non-teleological process, with mutation and random genetic drift being the random processes that feed selection. Evolution is what we term the interaction and results of all these phenomena when we combine them with genetic inheritance. Note that acquired characters can be inherited culturally, but not genetically.
Also, the bacterium isn't just capable of living in arsenic, it appears to use arsenic instead of phosphorus in all its macromolecules, which is pretty crazy. It brings to mind the astrobiological proposals of silicon-based lifeforms using ammonia as a substrate.