note: a delegate can submit a tx to SafeAPI even if it has zero signatures.

things related to "delegate" in Safe's tx svc api here: https://github.com/safe-global/safe-eth-py/blob/master/gnosis/safe/api/transaction_service_api.py

any safe signer can manage delegates by submitting a special message to the api.

Also, if submitter= is a delegate account or alias it should bypass this logic and submit it. I check elsewhere if they're a signer only for signature aggregation.

Originally posted by @banteg in #11 (comment)