Wow, when I read that you're calling him that, I was confused so I googled the guy. I saw he's from station "o bby" and I figured it would probably be a way to hint that you're into him. But then I kept reading...

After Tarkin repaired G7, he sent the MSE-6 unit back to TK-421 with a holomessage that indicated his interest in the stormtrooper as well as an invitation to visit his quarters to repair his aqualeisure unit. TK-421 felt flattered that he had caught someone's eye, telling G7 that, if he played the situation right, he could get them a transfer to Coruscant or anything else they wanted.

Source: https://starwars.fandom.com/wiki/TK-421

I'll summarize. TK-241 fucks an older coworker to get some favors. You calling him TK-241 was probably never interpreted as "haha you're a drone", but as "I'd like me some of that". You were never the smart-ass you thought you were, you were just propositioning a coworker.

And the fun part is, you're a fucking star wars fan. Poor guy was probably going back home to his wife with different levels of energy every single day.

Day 1
This random trekkie retard at work just called me tk-241, what do you think that's about?
Just ignore him honey, he sounds like a weirdo.

Day 2
Honey, he keeps calling me that. I should probably google what it's from.
[...]
Holy shit. Holy shit, Jen, come and look at this. The nerd is coming onto me. What the fuck. What the actual fuck. Oh Jesus. How do I get out of this? He wants to fuck me and be my sugar daddy. Oh wow.
Haha, the weirdo's got a crush on you! Aawww! Johnny's got a secret admirer!
This isn't funny Jen, he's older and he can talk to people and make it hard for me at work, how the fuck do I get out of this?

Day 3
Oh god, he did it again. He was laughing with his buddies when he did it today. I feel so dirty. Jen, what do I do?
Okay look, just stay calm. Lodge a complaint with HR explaining the situation. They probably can't do much with such a dumbass reference, and he may feign ignorance, but you want it documented. Then you talk to him and say that you don't like the nickname and to stop calling you that.
Yeah, you're right. Oh god, I hope he stops. I'm talking to HR tomorrow.

Day 4
He stopped. He finally stopped. I guess he's weird and creepy, but at least he can take a 'no'.
Did you announce HR anyway?
Oh yeah, they said if it happens again they'll have a talk. This fucking situation just makes me feel gross though, what a fucking freak.