I’d say that the end justified the means in this case. He knew that Snow could do it, and knew she’d regret it every day of her life if she didn’t, and she’d never be able to live with herself, so he gave her the nudge she needed.
I liked how in the flashbacks they had Charming giving Snow a kick so she could dig deep and be true to herself, and in present day they had Snow giving Emma a kick so she could dig deep and be true to herself.