It indeed seems to be that.
My initial thought of " will be disallowed on those tables" was "on the subscriber side". After all, why have a publication be of any effect if there's nobody subscribing to it.
But it appears the publication influences behavior, regardless of there being a subscriber, which feels counter-intuitive to me.
Thanks for stepping me through it.
And if my understanding is correct: if a table doesn't have a replica identity, any UPDATE or DELETE statement that happens on the publisher, for that table, will be refused.
That is how I read the sentence "Otherwise those operations will be disallowed on those tables."
Upon adding said table to a publication, future attempts to run updates and deletes will result in failures in the transactions performing said DML.
Feel free to experiment that the behavior indeed matches the wording in the documentation.
David J.