Their usage of "their" aligns with how English has been used for centuries (Wikipedia says 14th century), but more importantly the author's writing was the topic of discussion not their gender.

Policing other's pronoun usage is ideological, but that's your argument, not theirs.

Obviously, that is: statistically, all involved here (the SCP author, the HN commenters, you, me) are men, so saying "he" is very likely correct. If by chance someone here is nonetheless a woman she will probably speak up.

'Their' is practical not ideological - Sam could be Samuel or Samantha, and I didn't know which. Also, bring up the use of 'their' for unknown gender with Shakespeare and Austen, who both did it.

The only one being 'ideological' here is you, getting worked up over basic grammar that's been around longer than Modern English. Go out and touch some grass.