Slony functions unnecessarily lock pg_catalog tables for update but don't actually directly update them.
This prevents non-superuser users from calling functions such as adding a table to a set.
See commit diff here: https://github.com/mrkrstphr/slony1-engine/commit/1773d09be6c5df0c9b89d9f5494df2eb9bac7f24
This is preventing us from automating replicating new tax tables that come in through an automated process in our organization.
There appears to be a need to do the FOR UPDATE, in that this was introduced to prevent deadlocks that can occur due to needing to escalate locks on such tables.
A thought is to "hide" this query inside a security definer function, so that the permission could be granted to a more ordinary user. That seems a bit thorny, requires more thought.