Of course you are right. At that level, (triples) I just assumed that it would be an adult with a "history" (either on ice, roller, or, maybe, as a gymnast). Triples out of someone who started after age 25 without any "history" would be incredible I'm not saying it couldn't be done, but, well .....WOW!!!
No, it would have to be someone with a "history" who was in very good physical shape, (low bodyweight, no/few injuries, good leg strength), with adequate skating skills to support the jump.....Don't think it's necessarily an "age" thing, because I've seen Browning land triples and Boitano land a "Boitano" 3Lutz at 46! So....it can be done (by the elite who stay in shape, anyway). Saw another (unnamed) Olympic champ, (Boitano's age) and he only could manage a 3Toe, (listen to me, "only"). But he had put on some weight.
When you are talking about adult skaters who are doing high level doubles and triples, you probably need to clarify what kind of an adult skater -- at the adult level, you have 18 through 75 years of age. And, you have people who learned to skate as children versus those who started in their thirties or forties. I think Natalie Shaby skated as a child ( I might be wrong) -- she is a lovely skater and I am not taking anything away from her but someone who skated in their early years has that programmed into their muscle memory.....as opposed to someone who started a Learn to Skate program (just learning to stay upright and skate forwards/backwards) when they were 35 and then started landing doubles at 40.
Natalie Shaby and Liz Floriani both skated competitively growing up, and I believe Natalie won the Gold or Silver at Novice level in the Canadian national championships.