No. It doesn't stop being peer-to-peer digital cash just because people are using it for other things as well. Have you never seen a defaced banknote where someone has doodled on it?
Drawing a doodle on a banknote doesn't make it unusable or even harder to use, spam attacking bitcoin does. That's like saying that this forum is still a forum for discussion even if someone performs a constant DDoS attack on it 24/7 making it extremely difficult for
actual users to visit the site or post anything. Or better yet it is like if they also got paid to perform the DDoS attack!