Plagiarism - Clearly and obviously the words are not passed off as the author's own. The Service Inquiry report is referenced on page 2, as the first of 150 citations. One would have to be pretty dense to attempt plagiarism while in the same breath providing a download link to the source document.
Copyright - Is dealt with by the concept of 'fair dealing' (or 'use' - when dealing with Amazon one has to use their terms). For example, the 'reporting of current events' is an exemption to copyright. (Source - UK Intellectual Property Rights Office). The question becomes; at the time of writing was the issue 'current'? Yes, if one measures currency by media reporting, public interest/comment on the matter, legal proceedings, the ongoing links to other accidents or societal risk.
Would a fair minded person resort to such an attack when the real issue is why Sean Cunningham died in an accident that would have been avoided by simply following the instructions issued by Martin-Baker? Which, as I said, MoD denied the existence of, despite verbal, written and video evidence. As a past Service Inquiry President Homelover, you will know you have an enduring duty to report the emergence of evidence which would have affected your report. (Source - MoD). And did MoD pass this 'new' evidence to the CPS, HSE or police? That question has been asked of all concerned, and none will answer it. However, the HSE did reply to a FOI request earlier this year, confirming it had no evidence whatsover to support its allegations.
£4 to charity, and you could read all about it. Or I dare say the author might be persuaded to provide a free copy - pdf, Kindle or paperback?