I want to be respectful but if they say they don't care what pronouns I use for them, that feels like it puts the decision on me to choose what to call them and I guess I would probably default to "they" because choosing a gender for them feels weird... am I wrong?
they them is basically always safe! If someone specifically requests against it then don't but they/them is what I always use if I don't know or have multiple options. All I might add is that a lot of queer people get tired of being only called their AGAB's pronouns, so maybe don't exclusively use those.