I know nothing about this particular game, but with the vast majority of "why isn't game XXX on BGA" questions, the answer is because the publisher hasn't given BGA the licence to have an online version. (In many cases it may be because no-one from BGA has thought to ask, but there are plenty of popular games where I believe BGA have asked and been told no. No am not party to these discussions so can't comment on any particular case

)
And, while this is just speculation on my part, I suspect it's harder for BGA to get a licence for a game that is already based on some non-boardgame IP such as Judge Dredd.