What would they want with it?

They'd export it to Earth in exchange for other necessities. Airship parts, water, protein bars, TV shows. Earth would then use the deuterium for its 'free unlimited energy' fusion reactors.

To make enough giant H bombs to blow Venus' atmosphere into space?

This scheme would have some negative aspects.

BTW, hydrogen on Mars is enriched in D by a factor of 5 relative to Earth.

Deuterium might be the oil of the future as one can do fusion with it easily (in comparison).