As with every reasonably well-written argument between characters, both of them have legitimate points as well as glaring flaws:
- Tai has every right to invite as few people as she wants to witness her and Dora getting married; she's not obligated to invite as many people as Dora does, nor to over-obsess about who to invite or not. At the same time, though, she certainly seems to be letting Dora do all the heavy lifting in terms of organization.
- Dora has every right to put as much thought and effort as she wants into her invitation list, and is justifiably frustrated with Tai for, at least outwardly, not treating a momentous occasion for the two of them with more thought and seriousness like it deserves. At the same time, though, it's not justified to immediately flip out just because the other person isn't also a control freak in all things (and they wouldn't work long as a pair if they both were).
That said, on an out-of-universe level, it feels to me like this is a plot vehicle to sink Dora and Tai's engagement and relationship, both since they are older established non-AI members of the main cast (with all of whom Jeph is plainly and abundantly bored) and because a separate stable lesbian relationship exists (Faye and Bubbles) and the storyline doesn't necessarily need two running at once.