That's a REALLY dumb explanation. First off, there aren't THAT many Jedis to warrant carving out that much space on a cruiser that would be unused, like 99% of the time. It'd be like putting a chemistry lab on a cruise ship in case some esteemed scientists want to take a cruise. More to the point, Jedi don't DO "luxury" and wouldn't be ON a cruise to begin with.
Geez people - it's SIMPLE - Just say Kylo Ren ordered it installed - or better yet that Emperor Palpatine did (although the latter is a little trickier as I don't think his "Sith Lord" personae was ever public knowledge. But I bet you could get away with saying he liked to 'dabble')
We're way off the lore and Storytelling anyway (We offer a wide variety of light sabers in our gift shop on the mezzanine! Please stop by and check out our replicas of Darth Vaders lightsaber that you can own for your very own! Who's Darth Vader? Oh, we're not allowed to talk about him anymore.)