The winger, 23, has been registered in Sale's Champions Cup squad despite his signing not having been confirmed.
Cas are taking legal action after Solomona did not report for pre-season having "resigned" from rugby league.
"Clearly the sanctity of contracts has to be respected," said Wood.
New Zealand-born Solomona, who made his Samoa debut in a rugby league international against Fiji in October, was contracted to Castleford until 2018.
Tigers chairman Steve Gill denied they had sold Solomona at the end of last season, but confirmed that two rugby union clubs and one from rugby league had made approaches.
Director of rugby Steve Diamond confirmed Sale's interest in Solomona last month, and he is set to join fellow winger Josh Charnley in making the cross-code switch to the Sharks this season.
However, Castleford are prepared to take the matter to the High Court and have appointed London barrister Nick Randall QC and Leeds-based sports lawyer Richard Cramer to fight their case.
"It's bigger than just rugby league or rugby union, it's almost like a law of the land issue really," added Wood.
"Unilaterally walking away from things is not something you would condone.
"We've been in contact with both the RFU and Premier Rugby to express our concerns. They are aware of our position."
Solomona broke Lesley Vainikolo's record for the most tries in a Super League season as he crossed 40 times in 2016.
Rugby Football League chief executive Nigel Wood is concerned about the "implications for the game" if Denny Solomona's expected move to rugby union side Sale from Castleford goes ahead.