Coming from past experience here. A Go around with thrust at idle is very different from a go around with engine stable at approach thrust. If you Go Around with idle thrust rotate like you would normally do like you have been trained you will loose even more speed as the engines take a while to spool up. This is why a lot of operators want you stable by 500 minimums including thrust stable at landing thrust, so if you do have to go around the thrust is there available. My opinion and only my opinion is that the nose went up for the G/A and the speed decayed. Then they got the stick shaker before the engines had time to spool up.