It doesn't matter how people classify them or what tags they use when discussing those coins. It's all subjective. Those coins exist and perhaps someday the legitimate owner or a heir will appear with the right signing keys to spend them. No one has the right to point fingers and arbitrarily decide that some coins are lost just because they haven't moved for so long. Just recently we saw tens of thousands of bitcoins move from old addresses. Some were allegedly sold while others were moved to increase the security of them.

Everyone has the right never to move their bitcoin if they don't want to. That's ok just like it's ok to move them 100 times a year if you so please.
The BIP would only make sense if Phase C wasn't optional but absolutely mandatory. Still, I would love for there to be a mechanism to protect all or as many BTC as possible if and when a future come where a significant part of them becomes vulnerable.