If it was indeed the original script, the reason they changed to batteries is maybe not because "some exec" is an idiot, but because it worked better from a storytelling perspective.

Even if treating people as batteries doesn't make much sense as we are pretty terrible power plants, the message is clear and impactful. It is common for movies to oversimplify things, because they want to avoid having the viewer from being distracted from the main plot. It is tricky, as being too obviously wrong can breaks the immersion. I think the people = batteries analogy is a good compromise. Brains = computers, while technically more plausible would add a layer of complexity that could be a bit too much for a 2h action movie.