[The real answer was that Watanuki was kind of lonely and would have liked to have a friend or two. The thought of being judged by everyone without anyone to back him up was just a little daunting.

But he didn't say that. Those worries were very personal, and he didn't want to open himself up to criticism from Merlin. So he went with another answer instead.]

Isn't the saying 'power corrupts'? I don't want to become someone who abuses power.

[And then he realized the implications of his words, and he was quick to correct himself.]

Not that your story tells me King Arthur was abusing power, but people must have thought something like that, right?