I just tried it out. The game doesn't crash, it just acts a little strange with the blinking and all, just like you said. I guess the AI is looking for a unit for you to use when they are all gone.
I've never seen this before, but then again I've never had all my units destroyed before! I would assume its normal, unless somebody says different.
My god, they must have wanted this AK guy pretty bad. Talk about being outnumbered!