I would normally see the logic of that. But if they are so happy to keep him, why is Heldt talking so much about possible deal, and needing to deny it constantly, or say he is getting this or that offer. He seems like he wants to feed the machinery of a transfer himself, saying waiting for improved offer or how anything is possible. Like someone who wants to get a good deal now and sell him.
He doesn't behave like someone who wants to keep Draxler and sell in future at best. My best guess is he maybe realizes best value they can get for Draxler is this summer when the hype still lingers. Or other option is the player is keen and has told Heldt try to get a transfer possible this summer etc.