This is NOT a question about whether they/them is acceptable as a singular pronoun. I know some of you will have to die before you give that argument a rest, but I am starting here with the presumption that them/them IS an acceptible alternative to refer to non-binary gendered people. On to the question...
I was writing about a person who prefers the pronoun "they/them":
Talk to Abigail when they are a resident.
After I wrote it, I realized (assuming here in 2016 that "they" can serve as a singular pronoun - and more so here in 2017) that technically there is a lack of subject verb agreement. More correctly, I should write:
Talk to Abigail when they is a resident.
But of course that sounds terrible and wrong to my ear.
As they/them becomes an acceptable singular pronoun, do we amend the subject-verb agreement rules to use a plural verb with this singular subject?