Well, no.
Looking at the questions he has asked, and the assumptions he has made, I honestly do not think that he does know enough about BS 7671, and testing, to be able to justifiably sign an EIC/MEIWC.
I had a second part to my quote, but was interrupted. I was about to query how the poster could get from the initial query to being able to test to 7671 in under 2 weeks. I would also say that no electrician would just lend their test kit to a customer, even if they are local.
My point is that the person who did the work is the person who can certify. The validity of the certificate is another issue and I'd agree with your post bas, that this poster doesn't appear to be qualified to issue the cert.