Oh dear .. andothe statement, this time from a PHD no less ! Perhaps he should have done Critical Thinking at GCSE before putting anything on paper !
From your own quote "Yet the nearby parts of our galaxy in which we could observe such gas and dust shells contain only about 200 supernova remnants." Note the word NEARBY.
Our own galaxy is a bit bigger than "nearby", so his conclusion is drawn from observations of a fraction of our own galaxy.
Does that mean that the nearby part of our galaxy is special in that superrnovae can only occur there ? Or does it mean that Humphreys is ignoring things which don't match his beliefs ? Of course the latter would, as mentioned in an Abramson quote you used in another thread, not be scientific, would it ?
Looking forward to the next quote from you, complete with inconsistent/misleading statements.