Jobs emails are just conformation of what many have known about apple they are a nefariously unethical company. I tunes it self is a violation of a legal agreement they came to with a preexisting record company named apple. The agreement was that Steve job's Apple could not be involved in music. Apple has been caught evading taxes it sells substandard products for an inflated price. To top it off they actively discourage computer literacy.
Steve Jobs was known for being uncensored in his speeches, and as publicly made emails show, in his written documents as well. For someone who should have been well aware of how permanent writings over the internet can be, he is documented as asking how to block rival music download companies abilities to play their can be blocked from iPods. His emails have also been used in lawsuits against Apple in the past, which did not go well for the company.
Steve Job has a big impact on Apple and even after his death his words are still being scrutinized. Unfortunately for the Apple Company, Jobs' words are left for the judge to see in the latest lawsuit. While people usually get the right to defend their correspondence, Jobs won't be given this chance because he died and it could monetarily hurt the Apple Company in the lawsuit.
I don't think his email will even be evidence in the lawsuit, I think they will be thrown out and never spoken of again. His email are private and shouldn't be involved in the lawsuit what so ever. Apple will do just fine even if it is allowed in court.
Apple is one of the richest, most valuable corporations in the world. Even bad lawyers are not cheap, and Apple can afford to hire the best lawyers in the world to defend them. An email here or there from an ex-CEO will not be enough to hurt the company in their lawsuit.