What do you have?

[JugglingReferee]

Team A players do not need to be aware if B is playing legally, and since no legal throw-in has taken place, B's actions only confuse A, which I don't believe is fair to A. A TI violation makes sense.

In the reverse case, when A scores and is losing, and knocks the ball away, we can go straight to the T. In that case, B never had a chance to properly play basketball. In your case, B did have a chance to properly play basketball, so I less inclined to kill the play and let them inbound again with a stopped clock. The only option left is a TI violation or a T. This T would be too much, imho.