In this case, the structure is not in the list of public structures with a market, either.
The the structures location id is however leaking via the public market orders, since it does have other ranged buy orders.
You can gather structure locations ids from the markets/{region_id}/orders/ endpoint. All the location id > 100000000 are going to be structures. Then you can try those location ids on markets/structures/{structure_id}/ in addition to the location ids from universe/structures/. That should give you very good coverage. However, it will generate a lot of errors, so be sure to handle the ESI error limit.