A system crash in there would be either very dangerous or very expensive which is why they need a rock solid system.
You misunderstood what I was saying. Since it is dedicated machinery it is unlikely to receive external input which could compromise its security and therefore its stability. The kind of bug that could more likely affect its stability are all the other ones, and anyway, in this context EVERY bug is as important, so it's one of those rare cases where Torvalds point is valid.
a suse-based linux system for monitor & control of machinery
Theoretically though it isn't a good choice for robotics and machinery: if you use a monolithic OS and the system crashes, all the machinery crashes, which is unacceptable in the medical field among others (unless you have a good and stable fail safe server system up and running).