The arguments to your CLI command are being directly mapped into
PublicKey instances, but the arguments themselves are:
--min-signatures 1 /Users/...
Which is obviously not base-58 compliant. You'll need to parse the keypair file path in the arguments list, read the file to get the keypair byte array, then instantiate it using
Keypair.fromSecretKey(<uint8array>). You can then get the public key from the keypair after its instantiated.