I think an ideal version of this page would (a) think more carefully about how to define things, and include links to references that informed the definition or show that it's fairly standard, and (b) add a section explaining why proliferation/diffusion matters to nuclear risk, AI, biorisk, and maybe other things, and perhaps also explaining some similarities and differences in how it works/matters in each of those areas.
It seems plausible the key term used here should be diffusion, technology diffusion, technology proliferation, or (if we want to focus this more) AI proliferation / AI diffusion.
A downside of "proliferation" is that it has negative connotations and is associated with WMDs, which I think is actually fairly appropriate for AI and biotech but also does perhaps undersell their upside potential and could be seen as unfairly "skewing the argument" against openness with AI or biotech development.
A downside of "diffusion" is that I think a lot of insights and ideas and debates from nuclear/WMD (non)proliferation do transfer to AI and biotech. Another is that a quick google suggested "technology diffusion" mostly refers to a tech being gradually taken up and used by a large segment of a population, whereas I think really what's more important here is expanding a tiny circle of people who can use the very cutting edge techs to a small and then moderate circle, and what happens if one of them uses it badly, which then seems more like what's usually discussed under the term "proliferation".