If I, the Grumpster, were negotiating the relegation clause it would be something along the lines of:

IF the club is relegated then the club has the option to invoke a reduction in the players salary (the reduction will be detailed in percentage terms). IF, and only if, the club invokes said clause then the player is free to sign for another club (possibly subject to a minimum release transfer fee, which wont be viewed by the agent as unrealistically high).

It could be the only way that RUFC can entice players to accept relegation pay cut clauses.

In summary, both parties are mitigating against potential loss of income resulting from relegation.

I suspect the above will be what has happened.

If my assumption is correct and the club really wants to keep the player following relegation then they simply have to continue paying the championship wage.

Then again, knowing our lot, we've probably just said "aye, no worries pal, if we go darn that can clear off for nowt!"