Ichirin, Nazrin, and Shou, certainly not, given they were not harming anyone as far as we know. Murasa, however, was killing entire ships full of people, and should have been dealt with accordingly. Instead, Byakuren recruited her and allowed Murasa to kill the humans who were operating the boat that Byakuren was on when she met Murasa so there would be no witnesses.
doesn't mean that they should be killed...!Just because "they are youkai"