Answer:
False.
Step-by-step explanation:
An expert is someone who has a wide field of experience and expertise in a particular area of study. Added to that, he/ she must also have his opinions and writings be accounted for as credible and validated by others too.
So, if Gradin quotes his friend's opinions on his paper, it is not an expert's testimony as it is just the opinion of his friend. There seems to be no indication that this friend is an expert in the field and has enough credibility. So, it is false to infer that Gradin's friend's quote is expert testimony about the presented paper's quality.