To clarify what said above. If Dumbledore intentionally ties Harry to himself and doesn't want an alliance with Voldemort's former/potential followers, it doesn't necessarily make him evil or immoral, at least not more than anyone else.

In light of pharnabazus's theory, such a behaviour would make sense. Dumbledore is a very powerful patron, and he has obligations to his clients. An alliance, by it's nature, would mean compromises and the decrease of Dumbledore's power. It's very understandable that he doesn't want that. Not only does he need his power to protect his own clients, his clients also might not be very happy to see Dumbledore forming an alliance with Voldemort's former/potential followers. Can you imagine for example the Weasleys accepting Dumbledore's 'consorting with the enemy', so to speak? They may not leave Dumbledore patronage because of that (whose patronage they would enter in such a case?), but it would perhaps lessen their personal loyalty to Dumbledore.