I would also like the ability to disable this random event.
In one game I had it give me dozens (maybe hundreds, I didn't count) of covette class precursor ships. They all sucked, have something like 2 hp beam damage. I started trying to sell them... select, sell, confirm, select, sell, confirm... after 10 mins or so I gave up and just loaded the last save game.
Most of the time the game doesn't do this however, it just gives me one of the cruisers, either the cool looking one with a balanced config, or the ugly brick thats all armor and mass driver damage. One game it just kept churning them out. It seemed like every other turn began with "in what some have called a stroke of luck for us..." I had 8 of them, didn't even bother making my own ships for a while. I felt like I was cheating.