Hey there Wary,
I'm 65 and shoot a compound but I'll be returning to traditional by building my own (haven't since my teens, I've got the low-tech tools and a bunch of local juniper to put to the test). My friends shoot a little of everything and the point is to enjoy ourselves and build skills and participate in some hilarious "competition", if that's what you want to call it. Prickly pear in Texas makes some good challenge material--gotta be careful!
I agree with the point of a longer (wheel to wheel) bow for your dad, I think he would be so much happier and with quicker--and better results and there are some releases that get him up "on the string" rather than feeling like you're a foot behind the string--yuk! Never let hi-tech bow "sellers" do that if possible, I wihs I wouldn've been with him on that purchase. Inevitiably, they are "selling" not finding the product to fit the person for better results, they're like car salesmen, it's just a gizmo and then there's all the gizmos they sell to hang on 'em.
Cost? Yeah, my little compound cost less than many wonderful longbows/recurves out there and it shoots fine, it just lacks that "pizzazz" that "connection" that captured me so long ago. But the compound came about because of some wounded soldiers in my son's Company. It's a long story and a fun one, but I'm turning this challenge they put on me back around by building a decent self-bow and on the next trip to Ft. Benning to visit, we're gonna get out there and challenge each other again. You see my idea, right? Maybe get them to build there own stuff (more therapy that they don't realize) and then shoot with it, nothing more satisfying.
I feel for your dad struggling like that. Keep on edging him toward a longer bow, then a simpler bow, then...well, you know...