That is false. They are all descended from a single cell. In the absence of mutation, they are all either resistant or non resistant. If the original cell was non-reistant, and a descendent is resistant, then the descendant became resistant.
I'm unable to figure out what your difficulty is here. Do you want to parse the word 'became'? Or do you deny the truth of how I've described the experiment?
Naturally speaking; nothing becomes resistant, or is beneficial, or selects anything.
When a salt crystallizes from water, it becomes crystalline. There is no implication of purposefulness in the ordinary meaning of the word 'becoming'.
Question for edification: how does one determine the first cell is not resistant without killing it?
That's fine, so long as there is also no implication of purposelessness.
When a salt crystallizes from water, it becomes crystalline.
This is merely a chemical reaction and does not involve death. (again, see fire)
If you add a carcinogen to bacteria beforehand in order to cause a desired result is this the same as adding salt to the water? Regardless, you are correct in that the current theory of evolution involves no purpose which would otherwise imply some kind of adaptive quality to a mindless system. Neo-darwinism amounts to fortunate happenstance for survival and reproduction without meaning or purpose and similar to chemical reactions feeding off the environment and likened to fire