You were writing just yesterday about how a reviewer can only ever discuss how a particular book effecting them. It is therefore the reader's decision whether or not to take a particular reviewer seriously based on what he or she thinks that reviewer should have read before the book in question. It isn't particularly a reviewer's job to go off and read umpteen other books before actually reviewing the one he's been asked to read (that's an academic's job). Indeed, it could be said that a review without previous knowledge is fresher and more immediate.

There are SF readers who may question your ability to review SF based on your dearth of Golden Age reading. Almost certainly, most SF readers consider me a know-nothing. For my part, if I respect someone I'll listen to their thoughts on a book, regardless of their knowledge of its 'context'. Because, ultimately, Knight could read a billion zombie stories and still not really understand the genre way of looking at them. And you could read lots of Austen's contemporaries and still be unable to get your head around their style (for that reason, I'd recommend you don't bother unless you really want to). It's not what you read. It's how you read it.