Although i would not want to travel on that ticket but would like to know if it could be possible if i checked in online and just showed up.
In my opinion if you do the online check in and it works, you've just won yourself a free flight. When a CX check in agent sees that OLCI is done and verified, (i.e. you see ur boarding pass when you do the OLCI) that's a green light for them to go ahead. Now with the new system, you cannot do OLCI if there is any discripency (even if your ticket is allowed a date change at a fee, and you havent paid the fee, u cant do the OLCI).
So therefore if you want to enjoy your freebie, do the OLCI and if your good, then enjoy your flight....i dont forsee any problem coming your way unless a CX ticketing agent is reading this forum and this post.