The 17-year-old, who was sold to the Premier League giants for an undisclosed fee last week, has been labelled as 'the new Ryan Giggs', but Ridsdale insists the choice to sell him was the right one.
"I've always said we're a selling club and I've always said that every club in football is a selling club," he told the club's official website.
"If the price is right, you take a view, if the manager says he's prepared to let that player go then we'll try and re-invest the money to make the team stronger.
"We're not going to sell anybody because we have to, we'll sell people if the price is right and the manager thinks it's right.
"People don't understand the finances of this football club. The fact is, without selling a player each summer we can't sustain a wage that will allow us to compete in the Championship.
"That's just a fact of life in this stadium, clearly when we move in to the new stadium the whole financial dynamics change."