I think it's important to remember that they are very much human, and people do inhumane things.
Let's not delve into the nazi "we're just exterminating vermin" rhetoric. We are very much wanting actual people to suffer.
Note: I don't consider that a bad thing. They would happily cast the first stone, and I'm more than happy to shoot back. Don't start shit, won't be shit. MAGA just doesn't know how to go about the "don't start shit" part, and I don't think anyone should feel guilty about them fucking around and finding out. It's a pity they have to drag so many down with them.
Kim and Torres were guests of the Ocampa, and Kess knew how to get in and out of the shielded area. The Kazon were in the area but not directly involved yet.
So by beaming her up immediately, they would have had far more time available to do thing.
Now, whether they ask the right questions quickly enough to get in and out of the caves/cracks Kess got out through, who's to say.
Either way, if I recall correctly, the kazon knew not to fuck with the Caretakers station, so while I'm sure they would eventually have tested it to see if anyone was still home, it wouldn't have been as quick.
Ultimately I believe if Neelix had been truthful, the crew would have had enough time to figure out how to send themselves back to the alpha quadrant, and possibly been smart enough to set spatial charges to blow it up soon after they left to make sure the kazon don't get their hands on it.