, I don't see how your drivel warrants even the electrons it cruelly consumed. There's nothing to prevent the Kazon from boarding by completely conventional methods, and then e.g. throwing the explosives out of the nearest hole in the wall (or if none present themselves, arranging for one). These folks supposedly know how to fight, and lack of transporters is something they have learned to live with.
Among Janeway's good reasons for not attempting a return using Caretaker's suspect machinery could very well be the complete lack of evidence on it ever returning anybody to Alpha Quadrant alive. Odds of it returning even half the crew on a good day don't seem promising from what Janeway can
see, and this was not a good day. Doesn't mean Tuvok shouldn't suggest such a course of action, as it obviously is either Scylla or Charybdis.
They don't have easy access to water, but they have starships.
And that basically comes down to the definition of "them". The Kazon are enemies to the Kazon: going for water will mean giving up prime positions over the Ocampa treasure for the small group down on the planet.