what...? That's not even as bad as I was thinking. That's like blaming him for killing his teammates that are turning into zombies. There's nothing he can do for them and killing them is the least amount of honor he can do for them.
Ivanov was affected by the mental waves, too, I'm assuming. He was able to resist better than his teammates, but his mental was still messed up because of it, I think.
That is poor writing. Ivanov's revenge would be more understandable if those guys can be cured but union 0 refuse because low rate of successfull mental cure.