I don't know the details of how much it's costing us. A club's priorities can shift. It's pretty clear that Ole doesn't have much faith in Ighalo at this point, as Ighalo hasn't done anything in a while, and his minutes have dropped. So bringing in another backup striker option makes sense, also considering that Ighalo is on a loan deal and will leave mid season. The injury point is a fair one, but with him being brought in as a backup instead of starter, I think we can manage him well physically.
"Behave"? Really? How old are you?