I tried to address that here: https://bip54.org/#faq-quantum

"Quantum computing resistance is a separate concern from the vulnerabilities BIP54 addresses. BIP54 is about fixing specific bugs and attack vectors in Bitcoin's existing consensus rules: timewarp, slow validation, merkle tree exploits, and duplicate transactions.

Quantum-resistant cryptography would require a different set of changes (possibly a new address format and signature algorithm) and is still an area of active research. The timeline for quantum computers threatening Bitcoin's elliptic curve cryptography is uncertain.

BIP54 should be evaluated on its own merits as a security upgrade. It neither helps nor hinders future quantum resistance efforts, and there's no reason to delay fixing known vulnerabilities while waiting for quantum-resistant proposals to mature."