Cardano founder Charles Hoskinson has raised concerns about Bitcoin's quantum defense proposal, BIP-361, labeling it as a hard fork rather than a soft fork. Hoskinson highlighted that the proposal cannot protect approximately 1.7 million BTC generated before 2013, including around 1 million BTC attributed to Satoshi Nakamoto. This is due to the proposal's reliance on BIP-39 mnemonics, which early wallets did not use, potentially leading to these assets being permanently frozen. Additionally, BIP-361 co-author Jameson Lopp described the proposal as a rough conceptual emergency plan rather than a finalized specification, indicating that further development and refinement are needed before implementation.