should they have been there in the first place
Why not? Last time I checked we still lived in a free country - of course Julia may have changed the rules since then. Interested to hear any case you might make why they should not have been.
Would the result have been different if they had just overnighted with the tour group
Who can say, you know a crystal ball gazer?
it does give you somewhere known to go back to should something go wrong
While true, however there is no reason that in the normal course of events you need to plan for such. Operations are regularly conducted from locations where a return to land at the departure point may be impossible due to the nature of the problem you have at hand.