Contrary to popular belief, you don’t have to like it, or pretend to like it, or justify why you don’t like it, or even tell people that you don’t like it.
Totes fine to just dislike it and move on. For me I not only love LD but it actually brought me into trek fandom through the backdoor, and I’m currently watching TNG all the way through.
But I’m not diminished in any way by you not liking it.
Now as for your coworker, I recommend hitting him with a brick being direct and saying “I don’t like it, but you’re free to give me other recommendations you think I’ll enjoy.”