Here’s another source which seems unbiased:
http://www.patheos.com/library/roman-catholicism
“16th century The term “Roman Catholic” is not generally used until the Protestant Reformation”
I think that is a more accurate picture of the use of the term. For we know Innocent had used the term "Roman Catholic" prior to the Reformation.
Big difference between never and not generally.
Be that as it may, Protestants did not coin the term.
It was used by the Catholic church itself before the Reformation and it's not a great stretch of the imagination to call adherents of the Roman Catholic church *Roman Catholics* with NO malicious intent.
Just because someone chooses to be easily offended and tries to define the terms and the terms of use of certain words, trying to control the discussion through control of the vocabulary does not mean the people being accused have nefarious intent in their use of the words.