I don't know what's even the point of the Xyz Summon in here. You already can Miracle Synchro Fusion after summoning Goyo Defender and use its effect to summon a second Goyo Defender.
Just in case anyone's wondering why it doesn't work:
1. one of the Goyo Defender is still attached to Zenmaity, thus you can't use it as fusion material
2. as already mentioned, you already can fusion summon after summoning the second Defender, summoning Zenmaity would actually prevent you from fusion summoning, due to the above #1