Yeah, for hiring. But I feel like summoning them is the main way to get them. And by looking at the card, I don't see why you wouldn't, one way or the other, get at least few of them. Reinforcement tokens are a big buff for most of Hordes units and being target of "Survival of Fittest" somewhat hinders any unit other than eggs.
True, but if each fireteam summons one egg clutch per game, doesn't seem like a bad time investment to me. It's 6 scrip worth of models, after all. Of course, it's hard to say, since I don't know the flow of the game enough. Maybe one stagnant turn for Karkinoi is too much, but I doubt it.