I agree, the DShK drop is a waste of the slot. A more interesting option is the HQ glider: which can build a DShK, a 120-mm mortar and an M-42, this can also be combined with the Airborne Retreat Point. And one slot will be released for a more useful ability.
Did the Soviets use gliders?
Compared to the USF Airborn unit, Dshk drop is enough good option
Don't try to put too much in at once
Or give the HQ glider to the USF airborn company too