Answer:
Body Section 1.
Being Tom’s first royal feast, he´s completely unaware of etiquette rules that a real prince should already know. For example: "...he ate with his fingers mainly".
Body Section 2.
Everybody had already been told that "the prince was temporarily out of his head", so they had to refrain from showing surprise or laughter at the "prince". "The Hereditary Diaperer took it away with reverent manner, and without word or protest of any sort".
Body Section 3 - Third reason with quote
It´s only when Tom cries over his lack of knowledge about the proper etiquette to deal with an itchy nose, to which there´s no real answer: "there was no Hereditary Scratcher".
Conclusion
Not only Tom tries to hide his real self, but everyone tries to hide what they think they know about him, but it´s the etiquette rules, and their sometimes ridiculousness what ends up showing how difficult is to hide the truth when nature shows up in the form of an itchy nose.