I think there’s nothing wrong with going out with him–in general don’t tell your single friends who your dating(unless they’re involved)Any guy your friends went out with is prob. in the ballpark so go for it!
Many guys I went out with I refer to others it really works because friends are similar and now you should obviously care about her feelings but you should be confident to say I’m going out cause it makes sense–
if you get engaged just tell her I wasn’t sure what to do but I had to do whats best in my situation also try to set her up with one of his friends!!!!