It's pretty common for people to write greentexts where they pretend to be the other person in a scenario and write from their point of view in order to point out how strange the behavior in the original post was. It's intended to be parody, not something you actually believe.
An invalid turn would be something like placing a move on top of an already-filled square or outside of the 9 grid spaces. It seems obvious to a human that you can't do these things, but computer bugs have a tendency to do things you don't expect. And yes, passing a turn doesn't provide an advantage, but I listed it because it's still technically cheating.
It's pretty common for people to write greentexts where they pretend to be the other person in a scenario and write from their point of view in order to point out how strange the behavior in the original post was. It's intended to be parody, not something you actually believe.