Usage and Grammar

Q. Does the sentence “The historian has several sources at their disposal” make a proper use of the word their? Can it not be argued that the use of their in this sentence is acceptable to maintain gender neutrality?

A. Although many language writers and linguists accept the use of their as a gender-neutral singular, conservative editors will reword, especially when it’s so easy: Historians have several sources at their disposal. (Or better: Several sources are available to historians.)