Jump ball to start the game...both jumpers touch the ball legally. Are you saying you won't start the clock when the jumpers touch the ball? Because according to what you just stated, it wouldn't start since there is no team/player control in this situation...

The rule has already been posted earlier as to when the clock should be correctly started.

AI (OOB Player) never released the ball to be inbounds, so the clock would not be started.

SECTION 9 RE-STARTING THE CLOCK
ART. 1 . . . After time has been out, the clock shall be started when the official signals time-in. If the official neglects to signal, the timer is authorized to start the clock as per rule, unless an official specifically signals continued time-out.
ART. 2 . . . If play is started or resumed by a jump, the clock shall be started when the tossed ball is legally touched.
ART. 3 . . . If a free throw is not successful and the ball is to remain live, the clock shall be started when the ball touches or is touched by a player on the court.
ART. 4 . . . If play is resumed by a throw-in, the clock shall be started when the ball touches, or is legally touched by, a player on the court after it is released by the thrower.

In the OP, A1 (the thrower) never releases the ball although B1 is holding the ball. Because the ball HAS NOT been released by the thrower, the clock will not start.

In the OP, you are correct. But your blanket assertion that the clock does not start because there is no team control ... that is just wrong. Team control has exactly nothing to do with when the clock properly starts. The clock starts...wait for it...when the ball touches, or is legally touched by, a player on the court... And merely touching the ball does not create player or team control.

ART. 3 . . . If a free throw is not successful and the ball is to remain live, the clock shall be started when the ball touches or is touched by a player on the court.

In the case of a missed free throw, the clock can be started by an offensive player tapping the ball for a try on the rebound, or a defensive player taps the ball towards another player.

On opening jumps, the clock starts when the ball is tapped by one or both jumpers, unless signaled otherwise.

However as stated in 5-9-1 the timer can start the clock if they do not see the floor official signal start clock/neglects to signal (their discretion on what it means by ball legally touched), unless floor official specifically signals continued time out.

I always wait for the floor official to signal start clock before the clock starts. Rarely have I had to start the clock due to failure to see the start clock signal.

Generally when I see the start clock signal, there is player/team control established except during jump balls & free throw rebounds.

Jump ball, throw-in, free throw missed, in all cases the clock starts when the ball is legally touched. If the clock doesn't start until team control is established, it was started late.

I was thinking that, to be honest, but the way the rule reads even that wouldn't start the clock.

You need to show me a rule that says it's a violation for the defense to prevent the offense from completing a throwin.

Except for the fact that the player is supposed to be OOB....it is a throwin.

This, as has been stated, is just wrong.
But is this a retraction?

then there's this:

Key word here is "generally." Don't base your understanding of the rules on what you generally see happen. Quite a few times each game you'll see a throw-in pass tipped before it is controlled.

The defensive player crosses the plane such as 7-6-4

In other words, I was meaning most of the time.

As has been mentioned several times, the timer is not right there in front of/next to the play, so the timer has to rely on the floor official to signal when to start/stop the clock.

The player breaking the plane is the violation. It has nothing to do with completing the throw-in.

I find the thought of eagle using his discretion to be somewhat troubling.

So it's a retraction from your first statement. Understood.

Um, no. The thrower held the ball over the plane in-bounds. The defender grabbed the ball on the in-bounds side of the plane. At NO time, did the defender cross the plane out-of-bounds. That's why it's a legal play.

You don't have a friggin' clue whatinthehell you're talking about. And that includes when and why to start the clock. If you don't understand what we're talking about, by all means ask questions until you do. But DO NOT try to tell us what to do. Quite simply, you do not have the rules knowledge to be doing something like that.

Just a suggestion from the kinder, gentler JR.....