It doesn’t mean he was lying. What it means is that in the heat of the moment it was what he thinks he saw.
Keep in mind all of this played out in about three minutes before another officer got there.
Eyewitness testimony can be very unreliable and flawed at times.
The one person who did see the whole incident was the guy who tweeted the pictures. The whole thing played out right in front of his house and that is the guy the police need to talk to.
That’s your opinion. My opinion is that he is a liar.