[drdeca]

"Correctness" of word choice is determined by usage. I prefer a consensus where "they" is accepted as being possibly singular, so when I have no reason not to, I choose to treat it as being a correct usage.

I also tend to use it sometimes despite knowing the gender of the person I am referring to. This seems reasonable to me, because I don't see any reason why it is important to always specify the person's gender, when I don't need to specify who the person is, and doing so allows me to refer to someone without specifying a gender, should any situation occur where that would be useful, without anyone commenting on my word choice, because I would already be in the habit of sometimes leaving it out.

[gugagore]

It is also happens to be consistent with the way most academics refer to work, right? A single author will use "we" and others will use "they" to refer their work.