Can't "Buy Him In"???

[Freddy]

A1 enters game for A2. B1 shoots first of two free throws. Then A2 tries to return to the game to replace A3.

It seems correct that, according to 3-3-4, A2 should not be beckoned onto the court as a player. He's gotta "sit a tick", i.e. not enter until some time has run off the clock--("shall not re-enter before the next opportunity to substitute after the clock has been started properly following his/her replacement")?

In that sitch, is it correct also to say that the coach cannot "buy him in" with a timeout? I know that can't be done with an improper wearing of uniform (3-3-5), but it can be done in an apparent injury situation (3-3-7). I'm trying to find phraseology deeming it either permissible or not permissible in the case of the original sitch.

Any help? Or am I on the right track?