We have seen this countless times, casinos find some technicality to get out of paying for HUGE wins and as you said ... Bitcasino.io has a bit of a reputation. (if you can believe all the things that are posted here on the forum about them)
Indeed. Congrats OP and I truly hope that you will receive at least a couple of BTC.
I find it hard to believe that they can and will pay up the huge 171
BTC