His argument is already ridiculous, since they have limited acute vision and can not see camo people on where or who. The utility of w-elf acute vision in practice is far less than he makes it out to be. His statements would only be correct if it functioned like a ranger's acute vision, which it does not.

Another solution - Take away hide/detect hidden, give true acute vision and camo/creep.

Make them thieves operating in wilderness areas only.

I guess trapper may be the only issue, not sure if they can use traps in wilds.