Perhaps it will help to give an example which prompted this thought. Though please do not focuses exclusively (if you have something to add please feel free of course) on this example, because I am also interested in the general question listed in the title.

Take these propositions (for sake of clarity, suppose these are held by a cishet man):

1. I will only date someone who presents femininely
2. I will only date someone who has a vagina

I think it is unlikely that either of these two premises is themselves transphobic. (1) does not preclude trans women. And (2) does not exclude post-op transwomen, nor does it exclude pre-op (or never-op) transmen. However, when you combine the two propositions, you get a conjunction which entails one will not date pre-op transwomen. If one were to say "I will not date pre-op transwomen", it is not immediately clear that this isn't transphobic to me. At the very least, one might suspect such a stance to be influenced by transphobic cultural norms, upbringing, etc. Still, maybe this isn't transphobic either! Again, I am not making this post exclusively to raise such a question (though, again, feedback is certainly welcomed). My central inquiry, rather, is this. If the conjunction could be though transphobic, must one hold that one of the two conjuncts which comprises it is transphobic as well? Or, can one hold that it is in affirming both individually non-transphobic propositions that transphobia emerges?

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Similarly, can it be irrational to believe a conjunction comprised of entirely rational conjuncts? Can it be racist/sexist to have a set of beliefs that are all individually non-pernicious? Etc. Etc.