You are free to believe whatever you want to believe. I am free to believe whatever I want to believe.

The "Kill all gay people" one is fine in my opinion. The person is showing his/her perspective, we should listen to it, even if we largely disagree with it.

Here's my scenario for flagging a user:

Let's imagine a post titled "My Grandmother Died, Here's Her Story".

There's nothing gay about the post.

@skankhunt comments "Ur gay"

That's completely unrelated to the post, it is getting flagged.