that being said the drag would still slow them severely enough.
I mean a squid with a captured point vs one without.
That point carrier is gonna get caught.
At best I see the squid flying as fast as a goldfish. Though realistically it would be moving as fast as either old pyra or junker.
And just to inb4 clarify. The drag only effects forward and backward thrust and vertical velocity.
I would assume that if an airship would to go up, the cargo behind it will be pulled in an angle that has a component in the vertical axis - so vertical drag will be applied...
If you strap that cargo on a squid and a galleon, the galleon will be way behind the squid - same with any other ship. It has the best acceleration, and top speed. The thrust generated by the engines is a lot more dominant than the mass of the ship.
And of course that a squid with a cargo will be slower than a squid without one, because it adds weight to it. The point is, if you were to have a different ship carrying the cargo rather than a squid carrying it, it would be caught even faster by the chasing squid.
The only reason you would even consider taking a more slower ship with more mass is if it has better means of defending itself like more guns. So instead of running away as fast as possible - you will have a slow and steady journey but if someone attacks you, you take them down with superior fire-power.