[Ayumu sits up, still looking well.... unwell, to put it mildly, and looks at Rosalind sharply.]

How about option 3: Because admitting to anything one way or another in this instance could be a potential risk to my wellbeing?

[Listen, he liked Rosalind. He did. But speaking aloud about such things such as impromptu naps or illness or whatever this was was... well, stupidly risky.]