Earlier quoted context omitted.
I didn't really care for Old Man's War . It's a fun read, but it's popcorn. It was a bit too juvenile nanotech wankfest for me. Nominally it looks at subjects like long life, implanted AIs, etc., but it doesn't really do anything with them other than go "squeeeee look at the tooyyyyyys". EDIT: If you want to just bask in the sheer glory of superior firepower and gallows humor, and maybe even occasionally see somethin…
The greatest crime of Old Man's War is that it has a wonderful hook: we don't want 18 year olds, we want our recruits to be canny and wise and experienced, so we recruit 70 year olds and rejuvenate them... And then it does basically nothing with that. The 70 year old soldiers distinguish themselves in no way from the 30ish protagonists of every other scifi story.
If your entire setup is "But we want to use old folks!", then you should really delve into old prejudices, being unable to change worldviews, reflections on what it means to move to what is effectively a Valhalla of endless figthing and fornication divorced from your previous life, etc.
None of that stuff shows up though.
By contrast, look at the entire handling of, say, Mandella and the changing standards towards homosexuality portrayed in The Forever War, and the dissonance of the veterans with younger troops about the purpose of the mission and the validity of the government and its past actions.