Tang Mo was indeed manufacturing airships, because before airplanes were fully mature, airships could indeed do many things that airplanes couldn't.
For example... bombing!
The colossal airships completely surpass airplanes in terms of load capacity. The amount of bombs that today's airplanes can carry could startle you!
The Camel Fighter can carry a 45-kilogram Aerial Bomb—that's the total weight! That means, it could carry about two 20-kilogram bombs for a bombing mission. Even the large, three-engine biplanes can't compare in their carrying capacity to today's airships.
Beyond load capacity, the problem of range is also fatal. Airplanes are now essentially authentic protectors of airports, with hundreds of kilometers of combat radius, they are not viable as offensive weapons.
What's more, the Great Tang Group had some accumulation in the production of inert gases, which improved the safety issues of airships.