Szayel murmured, approvingly. "I'm afraid I have to agree with Kadaj," he said, as if such a concept pained him. "Nnoitra's data isn't yours to take."

Though Hojo could help himself to Kadaj as much as he liked, for Szayel Nnoitra, however, belonged to Aizen, and the scientific part of his data belonged, as far as Szayel was concerned, to him, until they got to Draklor and then he was forced to share it.

He wasn't prepared to share it here. To say nothing of the fact that Aizen wouldn't approve of Arrancar being studied by someone like Hojo.