Yep, that's The Chopper. It is very useful if you need to cut large quantities of balsa, styrene, or basswood strip stock, small dowels, or similar. Say you were going to scratchbuild a tiled roof or a hardwood floor for a building in a model train layout. One way to do that is to take an appropriate balsa strip, chop it up, and glue on all the individual pieces. To do that you might be looking at cutting hundreds of similarly sized pieces from the strip. The Chopper's great at that. The hinged blade is faster and easier to chop with than just a hobby knife. You can also screw on stops and/or mitre angles on either side, making it easy to setup for cuts of repeatable length & angle. So you can chop a piece, slide the stock, chop a piece, slide the stock, and so on very rapidly.
I originally got it for scratchbuilding miniatures wargaming terrain, like this:
Even on that little piece there's a lot to be chopped. The ladder is made from a dozen+ bits of styrene strip; the balcony, control panel, and some other stuff are framed in strips; and even the 100+ little bolts are chopped from a styrene dowel. The Chopper's great at that, rapidly making a bunch of repeated cuts in strip or dowel stock. So it's useful for model trains, wargaming terrain, and similar architectural or mechanical miniatures modeling. To a lesser extent I could see it being useful for building traditional stick & tissue balsa model airplanes. I think it's a touch pricey even then, but not terribly for a very niche hobbyist tool. I don't regret getting it, and have made good use of it in other hobbies.
But for rocketry I haven't felt a need for it. Unless you're making a steampunk model or something very specific, typically there's just not enough strip stock or dowel cutting to make it worthwhile. It's not good for cutting crushable tubes, so it's not even particularly useful for precisely cutting launch lugs or similar. Even for this Triskelion I'm just going to cut the little pitots/probes/whatever for the fins with a hobby knife because I already put the chopper away and it's not worth walking across my hobby room to get it out of the closet for just a couple cuts.