The way I see this, not getting into a discussion about the Varna System - Ashok is a 14-15 year old and if he can't be an idealist at this age when can he?! Surely the realism and cynicism will set in soon enough. This is the time when he has discovered he is a Rajkumar so an entirely new world has opened to him.
Ashok is not educated in the Shastrarth so his replies were from his heart, his own experiences and so it should be. If there is one person who knows the restrictive effects of Varna system it is him. Ashok has the same qualities but not the restrictions he faced as commoner. So how can he not think if there were no restrictions on human beings trying to choose their own paths based on talent it should be allowed?
Ashok's thoughts his individuality his liberal ways is what will set him apart. Why else would he be one of the greatest Samrats ever if he thought like everybody else?
A Samrat is not just Samrat of Brahmins and Kshatriyas but of Vaishyas and Shudras too. He has to think about their welfare changing their lives for better too. Ashok did not parrot like Sushim but he actually thought like a Samrat, for his entire praja. CVs are setting up for his uniqueness as Samrat this is what made him Ashoka the Great, not just leanings towards Buddhism.
Ashok just tried to unshackle the restrictions. Only an individual different thinking person can think this way, a Sushim just does not have the ability.