No... they could BUILD a knossos in there... saths are so huge... they could demolish one or two of em and build a knossos. And I believe they don't have ta do that, surely one of them would have packed a spare knossos.
Assuming they didn't, they can still demolish the saths or harvest the now floating around stuff and build one. Doesn't matter how long it takes, but fact is, as long as they are still there, they can come back. Somehow. Besides, wait long enough and one of the three nodes may reopen, or a new node form.
Sir, we discovered a new jump node in the fringes of Altair!!
Great, we will send a science ship to get to the other side...
Hey hey HEYY!!! NOOOoooo <static>
Hmm... lets send in another one...
Hey hey HEYY!!! NOOOoooo <static>
Hmm... lets send in another one...
Hey hey HEYY!!! NOOOoooo <static>
Hmm... lets send in another one...
<100 science ships later>
ITS CAPELLA!!! but where are the saths?
<translator error... some beings managed to build a terran translator...> 'right behind you...'
PEW PEW PEW!!!