Yeah, it makes no sense. It's the same as people shouting "speak for yourself" to people who are speaking for themselves.

This person is irrationally angry because someone has a different opinion than theirs. They made a similar post on this sub, also in response to someone sharing their opinion:

When you state your opinion, which is that, just an opinion, as a fact, you are objectively lying. So yeah, you lied.

The hypocrisy is staggering. To them, the other person's opinion is stated as fact (even though it isn't), but in the same sentence they claim their own opinion is objective truth.