That places its cargo capacity right in line with all other heavy lift vehicles. A market that by the time they get into will pretty much be all gobbled up by all the worldwide launch vehicles.

They are now left with two choices.
One.
Lift smaller launch vehicles and hope they can pull a profit by lifting more than one at a time. Not a good option.
If the first drop launch fails for some reason will they call off the second drop launch for safety reasons? And at that point is it safer to land with the rocket attached or just drop it and try to launch it and or watch it crash.

Two.
That monstrosity of a launch vehicle they were designing is big enough that if they reduced its payload it could be launched from the ground conventionally. Thus saving money on redesign and extra manufacturing costs for something different.
But no need for the Stratolaunch vehicle.
It also places it back into the lift area of other rockets already in production, tested and working. They better build it real cheap.

Every time I even think of the Stratolaunch plane all I get are images of the Spruce Goose.
It worked but did it ever really work?