Answer: NO. Do not give anyone access who you're not actually paying to do something clearly set out.
As the answers already say above. If he IS any good, he should be able to give you an assessment based on what's in the public domain (your website and SERPs results).
What to say to him? I would just tell it how it is: "It's privileged, private, confidential information so not given out and you should be able to give me a view without it, so send me a report and I'll consider it". If he carrys on: "If you're worth the money you should be able to give me a report based on what's in the public domain. Without it, I'm not even entering into discussion about it, good-day and goodbye"
However... he has, so far, failed to gain your trust... so I wouldn't give it serious consideration. Though I'm betting you'll never see a report to give consideration to.
It's nothing to do with 'non-disclosure'. It's to do with making it easy for him to fabricate stories and bamboozle you using your own data.