Okey, i cant see any reasons to earn credits with mining over a javascript implementation like CoinHive. As you say: "It's a good idea, but it's not going to earn you or Nulled anything of value, other than generating a lot of heat and using a lot of electricity, sadly." - I agree totally. Even i can't understand wich earnings NulledBB and CoinHive gain with this because you generate more web traffic then you could earn with this mining solution if you know what i mean.
Better to donate a litte amount of money to keep this community running.