My meager opinion is that once a person can shoot fairly well with the bow, the ethics should be taken on a shot-by-shot consideration.
My first trad kills were little gophers, some taken at 30 yards... I was pretty impressed with my shooting back then, and had a lot of confidence. I'm not a very good deer hunter, and never had a lot of time to invest in hunting whitetails, nor a great spot to hunt... but I shot a small deer from a tree at 15 yards a couple years later, and it died less than 10 yards from where I shot it. That gave more confidence. Then I got my longbow and wounded a doe at about 15 yards a couple years later... that was around 2011, and I was very disappointed with myself. I haven't taken a shot at a deer since, because even though I had some opportunities, and I am comfortable with my shooting.... I never had a shot that felt right. I've killed lots of rabbits and possum and grouse and raccoon and squirrels and chipmunks... but no more deer.
Fast forward to last year., and now I live back in Alaska. First of all, I have never shot a moose, but would like to. I have a 65# Black Widow recurve that I can shoot real well, and that's been my moose bow. But I got my first short bow (56" Cascade recurve) last summer and find that it's harder to shoot consistently. I went out grouse hunting several times with the Cascade and had multiple shot opportunities, but missed every time with that bow. I just wasn't up to snuff with it, but I like it so much that I wanted to get some grouse with it. Then one day, later in the season I took the BW recurve out for grouse, but hadn't shot that bow for a couple of weeks. Before I had a chance at any birds, I drove in and sneaked up about 25 yards from a legal bull moose. It was a very good opportunity, but I couldn't get those short-bow misses out of my consciousness, and simply could not justify taking that shot at that moose. After the moose ran off, I took a shot at a leaf at 25 yards, and nailed it. Maybe I could have done it, but in my mind, it just wasn't ethical. And it doesn't bother me at all that I didn't get that moose. Not at all.