I'm having flashbacks to Harry Potter fanfics where Dumbledore and his people's stubborn refusal to ever kill steadily has them losing the war because their opponents don't have similar qualms.
I'm not saying "heroes" should got out and have the lethal option be the first option, but it shouldn't be taken off the table. The lethal option is perfectly fine for people like the SH9 who already have kill order on them and the extra effort to take them in non-lethally could result in innocent lives being lost.