Oddly, given my usual annoyance at canon inconsistencies, one of the things I really like about Sabmyqis (also sp?) is that a lot of the information about it is hard to make sense of. Along with your question, even if the ships survived, how did landing parties survive away from their ships long enough (and wander far enough) to make the observations reported? It gives the sense of the robots there having very strange reactions, not consistent with normal logic but perhaps deeply embedded in their programming. So you might always get fired on in space, and immediately captured and led off for execution on the ground -- unless it's in the morning during the warm part of the year, when the robots would completely ignore intruders on the ground. It makes for a really eerie, scary scenario, as the Nth band of Scouts to land there, armed with patterns collected the hard way on previous expeditions, walks among the robots that are studiously ignoring them, wondering if they're 5 minutes away from learning about the "but attack immediately if it's cloudy" exception.
One thing that I recall being mentioned somewhere -- maybe on this list -- is that one would imagine that, especially early on, the powers enforcing the isolation of this system would concentrate heavily on making sure that the robots didn't capture a working J-drive. Canon already tells us that getting a working example allows for quick replication. It may be that the robots would ignore such an opportunity; it may also be they'd be boiling out into the galaxy on a crusade against everyone else a year later. Not the sort of risk you want to take. Thus it's surprising to the point of jaw-dropping that the Vilani were so willing to land ships there once they figured out most of what was going on.