This seems inconsistent with the way DescribeAddressVisitor is written: it allows for the case where the wallet has a redeemScript in it that can't be spent, yet the visitor will only show information on the redeemScript if it can be spent. I think it'd make more sense for it to be possible to have a redeemScript in your wallet that you can't spend, and for DescribeAddressVisitor to still show all the information known about the address in that case.