Of course they can question. It's their country. But Republic Days are sensitive events and I like to avoid being the party that shows insensitivity. Conversely, I expect others to respect 23rd March. Granted, that Indian officer took his cap off, but still, I try to cater to sensitivities and not use one person as the reason to target a nation.
It's about giving respect and receiving respect. It is a sensitive occasion. I mean, would you go to a funeral and complain about Biryani not being tasty?