This is precisely why I spend my time here, not there. We must shepherd our time, and spend our talents where they will receive the greatest fruits. There have been many conversions as a result of Catholic apologetics efforts here on FR.
If the same is true at the site you mention, excellent!
If not, revert to the "pearls before swine" position, dust off your sandals and move on.
Debate for the sake of debate is worthless.
Our efforts must be consumed with the salvation of souls, not matching wits.
I learned this the hard way, and its the reason I now avoid Neverending story type threads.