There were days in my dad's cancer journey when I couldn't do anything but cry. I'm talking giant sobs that leave your body in physical pain and dehydration from crying so much.
FFS. Leave the man alone. There are many reasons why he wouldn't feel up to being sighted in public, and they're all valid.
A member of the Royal Family he may be, but he's also a person. People are allowed to have off days and to not want to be picked apart for them.