What's your call - player entering without being beckoned?

[dkmz17]

That's what I thought the call should be, but the referees just blew the play dead, allowed the substitute to enter and then had a new throw-in at the original spot. The subsititute was definitely not at, or even in the area of the table,when the ball was provided to A1 for the throw in. Even if one official blew the play dead erroneously, if the crew recognized the error, shouldn't the officials have forced the substitute to wait for the next dead ball to enter?