Some of these perspectives on being old on NS are really screwed up. If you think someone riding park in their mid-twenties to thirties is old then you'll probably be the dudes who quit skiing at that age and get super out of shape, become workaholics and just straight lame.
Look at any of the top pro athletes in mainstream sports. Their prime years are in their late twenties through mid thirties. Your best skiing is still ahead of you! Yes you might have a slower learning curve and sure you might be a little less flexible and less inclined to take insane risks, but if you put the work in you'll be smarter, more creative, and better skilled skiers.
I've been riding park since before skiers where allowed in "snowboard parks". I'm now 28 and skiing park better then ever and having the most fun I've ever had.
Everyone on this site has soooooooooo much time left to ski park; don't worry.