[dogscoff]

Now, this does not sound fair, to the AI.

No it's not. There's nothing fair about it, but that's just the way it has to be when a bunch of semi-evolved steam tecchers squander my generosity and piss me off.

Seriously though, it might well open up a very easy conquest strategy for use against primitives:
-Gift them three or four starliners designated as "troop transports".
-Wait a turn or two for them to transfer all or most of their troops to the new ships.
-Capture the ships, use them to invade.

Hmm, I wonder if a variation on this could be used to strip normal proportions AI homeworlds of their troop defences?