Fans of the club staged a demo at Elland Road on Thursday calling for chairman Ken Bates to stand down after the sale of their captain, but Grayson has stated that the deal suits everybody.
"Jonny is hugely popular, so it's disappointing when someone like that moves. But it's the right decision," Grayson told The Mirror.
"We've agreed a good deal for a player currently unavailable through injury, who has six months on his contract and who could have left in the summer for nothing."
Howson made 225 appearances for Leeds, scoring 28 goals.