Non-creator user able to push to ssb repo

[aflock]

Testing out git-ssb, I published a repo to ssb://%GU8gn9wqwZxSg4gPeocV3bVWkw1JuvA4T3IwnML4CsQ=.sha256
with an empty README.md

@adridadou was then able to add the repo as a remote and push changes to it. Great! I pulled from the repo after awhile and got his changes.

Although the documentation specifies "You can only push to SSB git repos that you created, not ones created by other users."

Bug? If this is actually intended, is there a way to prevent users with the address from pushing (read-only access essentially)?