A bit of a history lesson to explain the situation.
Up until the new year, the Crusaders were based in South Wales. For the 2010 season it had been planned to play 2 matches "on the road" in Wrexham. This all changed when the team moved lock stock and barrel to Wrexham. Quite a few season tickets had already been sold to supporters in South Wales. So it was decide to play the "on the road" matches at the Gnoll to give supporters in South Wales a chance to see their team a couple of times without travelling too far. This was all with the sanction of the league.
The 2 matches selected to be played at the Gnoll were Quins and I believe Cas. The Quins match was postponed due to bad weather and has yet to be played. Due to this many people wrongly assumed that all future matches would be played at the new home of Wrexham, but the 2 matches have remained "provisionally" on the fixture list for the Gnoll.
It has been known to many people all season that the 2 matches were to be played in South Wales, but unfortunately it seems some clubs have been confused by the situation and assumed they would play their matches against the Crusaders at Wrexham.