It means it hasn't been, and thus needs more study in that regard.
My inexpert understanding is that mRNA vaccines such as this one are unlikely to have an impact on many autoimmune cases. In many, perhaps most, others, it appears from my reading to be likely that the generated interferons are not adding anything to the likelihood of developing an autoimmune condition that wouldn't eventually already happen. (It might be the nudge over the cliff, but so might have the next common cold you catch.) But it should be tested to understand, regardless.
My inexpert understanding is that mRNA vaccines such as this one are unlikely to have an impact on many autoimmune cases. In many, perhaps most, others, it appears from my reading to be likely that the generated interferons are not adding anything to the likelihood of developing an autoimmune condition that wouldn't eventually already happen. (It might be the nudge over the cliff, but so might have the next common cold you catch.) But it should be tested to understand, regardless.