Which LLMisms are you seeing in their post? Their grammar, word choice, thought flow, and markings all denote a fully human authorship to me, so confidently that I would say they likely didn't even consult an LLM.

lol. I did use a lot of short sentences, that’s my bad. But please read through [1] and compare my text onto it, it may enlighten you on how to actually spot llm writing.

[1] https://en.wikipedia.org/wiki/Wikipedia:Signs_of_AI_writing