Meeting just about anybody would always be a risk to the future of, well, the future.
OTOH, if they just flew off to deep space and shut down the engines, odds are that nobody would ever find them. But that would be a dull sort of way to spend the rest of your life. So why not land on, say, Ceti Alpha V and set up shop there? The databases would surely reveal at least a few such planets where nobody ever went and which never became anything significant, and the heroes could no doubt take a few treknobabble precautions against their lifesigns ever being detected.
...It would be a rather weird kind of a society, to be sure. A religion that forbids contact with the universe and predicts absolutely certain doom at a known date and time; I'm sure the descendants would at some point begin to question the wisdom of that all. And when they found out that their seemingly mad priests and scriptures had in fact been dead right about everything...
Timo Saloniemi