THis is rather like saying Protestants would be Gnostics if they were Gnostics.
More to the point, most Protestants would abhor many of the beliefs and practices of Gnosticism. To then claim that they are just a type of Gnostic is not only silly, but offensive. It is no different than a Protestant claiming that Catholics are cannibals who believe in witchcraft.
Everyone knows that Catholics believe that their church is the keeper of the Truth. However, to say that Protestants only maintain a bit of Truth thanks to the Catholic Church is also a little silly. It is restricting Gods actions to the Catholic Church, which is not only arrogant and illogical, the Catholic Church doesn’t even teach that is the case.
I am really flummoxed that people want to make such foolish assertions. It seems they have no interest in understanding Protestantism, or Gnosticism for that matter. Do people not realize this also translates in to misunderstanding Catholicism itself? Not to mention that it is dishonest and uncharitable. Is “proving” Protestantism is wrong actually more important than justice, charity, and Truth? Do people really believe that the end justifies the means? When you leave behind Truth, you leave behind God.