Indeed. Maybe my English skills are fading with time, but my impression was that it works there because it's unclear who you're talking about. "Some other" is singular, but multiple people could have noticed that so it makes sense to use the plural there. It's kind of like how in American English they say "France _has_ won the WC", but in British English they say "France _have_ won the WC" (because a team has multiple people).
But saying "The boss fired me. They are awful." sounds no different than "The boss fired me. He are awful." or "They is awful." My auto parser is failing and I have to think it through.
Note of course you don't say "they is awful", you still conjugate they with "are", even when singular. For an unknown person, for a specific person, either way.
But saying "The boss fired me. They are awful." sounds no different than "The boss fired me. He are awful." or "They is awful." My auto parser is failing and I have to think it through.