"Why do you think I didn't notice it, and why do you think it is curious?"
"Your question makes me think that, even though you noticed the quotes, to the extent that you used them in ... of quotes to question the concept of good English. This is presumably just the opposite of what the OP intended."
Presumably single quotation marks are less 'scary' than double quotation marks?
He could simply have been indicating awareness that the concept of 'good' English is not universally accepted: that there are those who simply regard it as hieratic rather than demotic.
John Briggs