Allow decentralized issuance for RGB contracts
Right now RGB contracts may have a single genesis (non-committed) and the rest of transitions must be committed with bitcoin transaction graph. For a decentralized issuance a non-committed multiple issuances are required; this can be implemented with allowing RGB contracts to have multiple (sub)genesis under particular genesis/schema
How does this differ from using a multisig to create genesis?
Signatures are not used with genesis; but you may think about this as a form of "distributed genesis" created by many parties w/o coordinating with each other. However this mechanism works even after genesis, deeper in RGB transition graph.
I meant, creating a genesis from a msig keyset. Is that possible? Where the controller of an RGB asset is actually made of multiple keys?
You do not need genesis for that; all you need is to assign secondary issuance right to a bitcoin transaction output with multisig. But you can't dot a "multisig" primary issuance anyway: it is not controlled by signatures anyhow.