Isn't Peter Todd working on Mastercoin? Why would he propose that?
Think about it. Mastercoin is a competitor to Counterparty. Mastercoin is already aware of, and working on solving this storage-in-multisig problem.
Peter Todd's proposal simultaneously (a) benefits Mastercoin, (b) disadvantages Counterparty, and (c) presents a proposal that portions of the developer and mining community
already find agreeable.
Maybe the devs at Counterparty should learn Peter's proposal and we explore how we might participate to benefit alongside Mastercoin?