Thought the same thing. THEM?
Technically, that is not an error, according to the way that writing is now taught. Students are told to use the plural - because it is non-gender specific. Apparently, that is also correct according to grammar, but rarely used until now.
Examples:
The student who achieved the highest mark in biology was congratulated, and they will receive a prize.
Instead of:
The student who achieved the highest mark in biology was congratulated, and he will receive a prize.
I suppose a better example would be about a student who scored a chance to become HIV positive, but I’ll leave off now ...