I really don't see what Momo and Marten are doing as shipping though. Shipping is talking about romantically connecting two characters that aren't connected in the story. Or people and real life, though I don't see that as often. Momo is an active participant trying to get Marigold and Dale to hook up. Marten is just commenting on the obvious attraction between the two of them. Now someone coming along and saying that Marten and Swen would be perfect for each other and should totally hook up... That would be shipping. Even Marten/Claire is borderline, because of the somewhat mixed signals from the wedding party.
Ship is short for relationship, so I think the definition is considerably broader- pretty much any speculation about character (or real people) interactions is shipping. Which is why I personally am pretty tolerant about it, and kind of shake my head once people freak out if shippers even hint at sexuality, or authors act shocked- shocked! - that fans may be enthusiastic about relationships they didn't intend or are unlikely. Like the aforementioned Hannergold thing.
As to Dale and Marigold and their pornographic predilections, I expect that both will be aware, but not experienced, with any such material based on their treatment to date. Read; both will have inexplicably completely avoided explicit porn of any type for the sake of Comedy.