I think there's a misconception about Capricorn Asc and Saturn on the AC. I don't think the native actually gets "younger" as they grow older. Age doesn't work that way in the real world. It's that time stopped for those people earlier, so as they're getting older in age, it seems like they look "younger." Saturn is the ruler of time and timelessness; "classic." The word classic carries the connotation of surpassing time barriers and being relevant longer. When time stops, technically, you don't get "younger," you just stopped aging.
I don't know about Cap Asc people because I've only ever met one (as far as I know). This person is a friend and she's 24-year-old (young) Gemini Sun with 4 planet Gemini stellium (abundant youthful positions) and have Cap Saturn on the Asc. She doesn't look "old" for her age, but she doesn't look "younger" than her age either. I've known her since she was 20 and for the most part, she's only aged slightly. But if you think about it, she's still very young so there's no way for me to tell at this point. Maybe when she's 40 and I see her again, then I can say with accuracy, "Oh looks like the clock stopped for at 25 years old."
I have Libra Saturn on the Asc and for the most part, I've aged very little. It's true that when I was about 21 and under, I looked "older" than my age. I showed a school picture of me at barely 5 years old to my co-workers who had known me for nearly 3 years and they all thought I looked like I was 12 or 13. Now at 32, people see me at being 20-22 years old. My skin is still very smooth, I exercise regularly, I haven't eaten meat in many years, I wear clothes in Junior sizes, and most of all, I have an "immature" sense of humor where it makes it easier for me to relate to people who are either much younger than me (like in their teens) so people think I blend in with them, or mesh well with those who are much older (like in their 50s+) to where the vast age difference makes my youthfulness more prominent. As for people around my age, I have very little in common with and find it boring/tedious to be around them or even to converse with them. The basic is, that I didn't get "younger," I just stopped aging sometime around 21/22 (at least for now HAHAHA), but my age has exceeded my looks by a decade.