Technically, any horse who is registered is not a grade horse. So your horse wouldn't be grade
I don't have anything against grade horses considering I technically have two. However, I don't call them grade. One is 100% TB (racebred but never registered) and the other one is registerable with the AWR or AWS (I can't remember which one accepts draft crosses). So, as long as a horse is registerable, to me they aren't grade but I know that's not the actual definition. I just don't see the point in calling them a grade horse when you know their entire pedigree!