I can only speculate on what role ML might be playing in pharma; my own limited imagination has trouble guessing which possible uses would require "validation" in the classical sense. For example: any new treatments developed with the help of AI wouldn't be accepted just because an AI was validated, and my gut instinct is that it is unlikely that AI would be used to play a role in a manufacturing process (e.g. mixing).
From my acquaintance with AI/ML in/as medical devices, they are mostly about making inferences from a big dataset (e.g. a medical image); too big for a human to analyse methodically and consistently (and non-intuitively, i.e. like a radiologist would observe an X-ray image). In that context, validating the AI does not equate validating the device (or the design). While the latter means building a solid (preferably as objective as possible) case that the device fulfills / will fulfil the user's needs, the former simply means that the AI will "spit out" the right answers ("right" in this case means close enough to what a human expert, e.g. a radiologist in the case of making inferences from a medical image, would "spit out"). Technically speaking, AI validation is similar to AI training, and to use a human parallel, it's like the test at the end of the course, that checks that the training was successful. The main difference is that in the training stage the errors are used for improving (the model), while in validation it's not done - there's only a "pass or fail" result. Of course this description is a little simplistic, but you get the gist I hope.
At this stage I don't think AI is seriously used for "developing new treatments" or the likes. I think it's just not there yet. Maybe it plays some modest role in that arena, but I think it's likely that wherever it's claimed to be more than that, it's mostly marketing inflation.
the book reads (to me) like it didn't get a particularly serious pass through an editor.
This seems to be the case with so many nonfiction books today, that would have otherwise been quite good.