Sheyan knew how destructive a large group of Mutalisks could get.
Because on planet Pandora, Sheyan already had the experience of bombarding Viperwolves packs with a large amount of Mutalisks. The acid spores the Mutalisks sprayed and the splash damage they caused were truly an amazing sight. But now that he was about to become the target of the acid spores, he found nothing amazing about it at all.
However, the main weakness of the Mutalisks was also widely-known – they had insufficient range. Their attack belonged to the category of mid- to short-ranged attack, so if a large number of Mutalisks wished to attack a certain target, they would inevitably have to cluster together.
And when the Mutalisks grouped together, the Protoss' powerful Psionic Storm could easily eradicate them. They also had to be wary of the Archon's psionic shockwave, which was also an AoE attack.
