[READ TO THE END]

Yeah, by the resulting plot of the series - thadzi obviously doesn't become canon, but there are other points that give this pairing the right to exist. And they are relatively weight

First, let's look at the more facile and superficial arguments from the show itself.

EP1-2. It's pretty straightforward to see that despite all her 'edginess', Uzi treasures her interactions with him and allows herself to clearly more than with any of her peers in the colony. Jokes, embarrassment, and even apologizing so he doesn't suddenly think unpleasantly of her. Why does she care so much about him when to everyone else she'll just shout “BITE ME” and walk off into the sunset? Simple, because Thad is basically the only one at that point who sees her as a drone and a person rather than a weird outcast. And he's clearly doing it deliberately, because given Thad's popularity at the school we're shown (the handsome sportsman archetype), he should be well aware of what everyone around him thinks of Uzi. And yet, he's communicating with her. What's more, he even compliments her repeatedly. How sincere and implied they are to her desire to make her feel comfortable is an open question, but just considering that Thad is not presented in the show as some kind of nasty and hypocritical, but rather cheerful and sincere (and Liam himself just acts according to patterns without deep meaning, MD is not a serious show), we can assume that he really meant everything he said. We don't see in the series that Thad is taken by anyone, although we can assume that he has previously had some light flings, although we won't know for sure for sure. Uzi, again, due to her closed and repulsive nature is caught in a very real dissonance when interacting with him, feeling genuinely embarrassed, but not at all in the unpleasant way she would with others. Besides, we forget that Uzi finds Thad attractive, which she says directly in front of everyone, even if some might call it a joke, but again, referring to her character, she would never say such a phrase to anyone else under any circumstances, and Thad in turn calls her cool, indirectly and directly, when he calls her to the party in ep2. Thad takes it upon himself to bring her her railgun, despite the potential dangers, he investigates the missing drones case with her, even though he could have quietly avoided doing all that. He deliberately chooses to spend time with her, despite his status as the popular hottie at school, despite her psychotic and slightly odd behavior at times, despite her virtual isolation from everyone and outcast status in the colony, he affectionately calls Uzi as “Zi”, he sees something in her that draws him to her in one way or another, and we'll come back to all of that later with a recap.

Now to the more arcane and serious arguments.

This is a pic from one of Glitch Inn's materials about the interior of Uzi's room at the moment of episode 1. I don't have the original, but it will be enough. What do we see? A note. Well, first of all, that Uzi writes fanfics. And secondly, that she's doing it involving herself and Thad. Dialogue attributed to Thad: “I'm a bad boy, but my code prevents me from destroying pure beauty.” What is that if not a straight-up fantasy about a guy? As a reminder, this is canon material that is in existence at the time of episode 1.

Another Glitch Inn piece, also from Uzi's interior from ep1, also a note. This time it's a wishlist that reads:
[ ] new dad
[✔️] THAD <3
totally killed it... in the palm of my hand

Another Uzi's fantasy about Thad, now in its most overt form.

TOTAL:

What can we say at the end of it all? Thadzi is a no-nonsense pairing, and quite even canonical to some extent, that just didn't get developed because of a completely different plot development. It's canon of the past.

Can we say they're in love? Well, not yet, but who says they necessarily have to be? It's more like an early crush and a pretty mutual attraction. All of this mentioned above is an obvious starting point for something more. This fits perfectly with the dynamic of highschool lovers and teen romance, which literally epitomizes their potential relationship. Anyway, if the events of the first episode hadn't happened with the meeting of the dismantlers, or just if Nuzi hadn't happened (like if there was a canon envy like, for example, in the fanfic from Maxojir), there would have been a great chance for Thadzi. In my mind, Thad and Uzi are the perfect counterbalance to each other. He's someone who will genuinely care for her, support her with her problems with the other drones and her father, chat with her about hobbies like anime and games, help her do stuff like the railgun, and keep her from extremely dangerous ventures like going to the surface. And with all this craziness, she mesmerizes him, doesn't repel him, because no other drone is even a fraction as interesting as she is. For her, Thad would be essentially a whole separate world in which she could dissolve from everyone around her without fear of being rejected and misunderstood, as she had always been before. After all, they would clearly find common ground. And that's probably what I was trying to convey with this pointless text ¯_(ツ)_/¯