What if Shavepate really didn’t care whether he killed Hizdahr or Dany ? What if what he desired is sole power over Meereen ? If he kills Hizdahr, well at least one of his enemies is dead & he can get rid of Dany later on at his convenience. If he gets Dany, then he can raise a hue & cry about Hizdahr being Harpy & murdering Dany, and depose him with the help of his loyal Beasts+ freedmen who are loyal to Dany & opposed to Hizdahr+ the Unsullied if he can convince Ser Barristan like in the OTL.