Not seeing him really wasn't an option at this point: there's the shouting, the snarling, and the fact that they're not exactly on the edge of the city all meant someone was seeing this. And Lyall would not be coming easily. When he realized he wasn't getting anything edible out of the blade in his mouth, he finally let it go and started clawing at the pavement in an attempt to get free.

Perhaps interestingly, he wasn't actively trying to attack Hajime except incidentally in an attempt to get free. Giant bugs, after all, did not smell like food to a werewolf.