I totally agree with both your concern, as well as with - even if not mentioned - your frustration, for try as I might, there doesn't appear to be any guidance on this topic!
Whilst it may well be that the mere mention of "zip and link beds" don't occur within the vocabulary of other Countries (other than the UK's), what I find even more strange is that amongst the various sizes of beds, "SuperKing" as a size, isn't mentioned at all (but then again, there isn't any mention of an "Emperor" bed, either!)
At the moment we have 1 x SuperKing bed that can be separated into 2 x 3foot wide single beds when required, But we can't list the bed as one SuperKing as Airbnb don't list such a size.
On the other hand, as Single beds ARE listed, we're able to say that we have 2 x Single beds, but NOT that they can be linked together in order to make one lovely 6foot wide (SuperKing) bed!
To be perfectly honest, I'm very surprised to discover that apart from the one comment (and only one, until I came along) no-one else has a problem with describing what they have and provide - bed-wise - for their own Guests? Unless, that is, that no-one else apart from yourself, the author of the other comment, and - of course - myself, actually provide the flexibility of SuperKing beds, such as wot we does?!
Personally I believe that this particular matter is more for Airbnb themselves to resolve than within the Airbnb Community, as here we can discuss and suggest, but don't have the ability to add "missing" facilities.
Having said that, perhaps an Administrator on here could take up the matter on our behalf, as I can't really believe that the thousands of zip and link bed bases and mattresses sold throughout the world can ONLY be described on Airbnb's portal as 2 x 3foot (90cm) wide beds.
C'mon Airbnb, us Hosts are trying to give our Guests a wider and more flexible range of beds, suitable for an equally flexible range of Guests! so please could you give us the ability to accurately describe what beds we have and in which way they can be transformed into something even better?!
Thank you (with much anticipation)!