Rings that thick are rare. I've seen them that thick in heart wood, so a long time ago it was sapwood. But I wouldn't say it would have been better to leave it, but it would have been easier. Early and late wood are strong in yew. So ring thickness isn't all that important. "They" say thin ringed is better, but I've yet to see a noticeable difference. Looking forward to seeing this bow done.
Eric