I could go with that.

I can buy the reasons given. It just seems off.

Take a defensive rebound and players transitioning. A defender is out of position and moving towards guarding his opponent. An offensive player (say a post player) is simply moving from defense to offense to get to his position. The fact that he has to stop because "he is simply in the way" is a difficult sell to me. The logic makes sense, but this also negates the fact that the offensive player has a right to his spot on the floor and is clearly not a screener.

Sometimes Fans Feel Like Nuts, Sometimes They Don't ...
 

Officials see this situation a few times each year, two offensive players and one defensive player on a breakaway, all heading toward the basket, with one offensive player between the ball handler and the defensive player.

And, or course, the fans, and maybe even the misinformed coach, are yelling for a "Moving screen".

Most of the time we just smile and think to ourselves, "Yeah, it's certainly a moving screen, but it's not illegal because there's no contact, a moving screen is, in itself, not illegal".

And then occasionally there is contact, the offensive player without the ball, while moving, contacts the defender, preventing him from defending the ball handler.

That's an illegal moving screen, more accurately known as a team control blocking foul.

For me, I judge it based on what actually happens. If A2 is attacking the basket, they'll often be a step ahead or at least pressing the pace, hoping for a pass, I got nothing. However, if A2 is clearly running interference and not trying to attack, A2 is screening. It is certainly judgement.

Why do you say the offensive player is clearly not a screener. Being a screener isn't something B1 has to designate. If A2 blocks the path of another player, deliberately or not, A2 is, by defintion, a screening. Screening is the effect of the position, not the intent of the action.

Additionally, a defender has the right to the path to play defense and such path has to be blocked (screened) at least 1-2 steps before the defender gets to a spot (moving defender).