Good point, but you forget that race attack can start when quantum-resistant address is available for use. If it's deployed before quantum computer with sufficient qubits exists (some source mention 1500 qubits for 256-bit ECC), then the owner have big start.
right, and you think that applies to everyone on the network? is satoshi gonna move his coins to quantum-resistant outputs too?
Obviously no, the point is to reduce amount of Bitcoin at risks. Besides, this problem doesn't have solution where majority could agree.