Non-violent antags can be spicy if the player knows how to go about not being violent, while completing objects, and all the meanwhile being interesting.
For example... I actually made a mime kill himself, without a word, by using words and other people, creating a web around him. Basically, if he was my target, boom, non-violent, and fun for everyone involved. Although, a great option as mentioned would be "options". So like. Yeah, a less violent antagonist option isn't necessarily bad. It can let people who are more RP based, and non-robust still be a fun role to play around and as.
then again what do i know im just some lurker (edit: I actually once asked some admins if I could get no killing objectives. They instead gave me stealing objectives. From each head.)