You may be right, but Apple execs are accredited investors worth tens to hundreds of millions and as such are easily able to invest in private companies, so tha

You may be right, but Apple execs are accredited investors worth tens to hundreds of millions and as such are easily able to invest in private companies, so that doesn't rule it out. Nepotism is another possible explanation if there are any connections there. And while it wouldn't be illegal while they were private, it would still be immoral, and it would become illegal when not disclosed as a risk at IPO. It could also further jeopardize Apple's standing with regulators, since they profess to apply their rules fairly and equally without secret deals (which is transparently ridiculous but Tim Cook said it in congressional testimony so it would be perjury if proven wrong).