The antag mechanic shouldn't be optional, BUT it shouldn't be in mentor matches either. Mentor matches are already a big enough handicap on players, let alone dealing with the handicap + an antag.
The antag is designed to cause chaos, this is true, however this kind chaos in mentor matches is unnecessary as it's already chaotic enough as-is.
I find it amusing PvP supporters basically want to decide for others that PvP shouldn't be optional. Every other game this would be a ludicrous position, an invasive bossy position even, but in this game PvPers take it upon themselves to tell others how they should play the game and how they should enjoy it. Fucking amazing, and arrogant.
Keep in mind that it WOULDN'T influence how THEY would play the game. they could go on playing the game with PvP in it as much as they want, but somehow they believe how OTHERS are playing the game would influence them. Like Evangelicals and gay marriage, it's got nothing to do with you. You want PvP? Good, mind your own business and play PvP. But to say that those who want the option shouldn't ask for it or enjoy it is a bit totalitarian. Especially when many of us have already conceded that PvP should reward higher amounts of gold and faction. But we still heat these controlling types wanting to silence others and tell them to fall in line or get out.
NOPE. That just makes me want to fight for it even more. You guys put me in a fighting mood. You piss me off, get me all riled up inside and make it so that I'll keep asking for it even more.
I guarantee this game will slowly die if they refuse to make PvP optional. Warframe started slow and now thrives because they have exclusive PvE. Street Fighter 5, For Honor, World of Warcraft, Dark Soul Series, etc... to list a few have optional PvP and PvE. Some they reward more for PvP, some they reward differently for PvP, but they have the option. And because of this they succeed.
Don't use the "But if they make it optional no one will do it" because that's just an admission to it being lame. You would want people to partake in a system they otherwise would avoid but are forced to have to do. They could incentivize PvP, that is the healthy way to go about it, but forcing people is ALWAYS bad.
PvP should definitely be optional. And there really isn't any good arguments that have been made against it. Just a predatory logic for those who want unwilling opponents to grief.