I read that blog back in 2013 just before my first flight into CIA. (I was doing a Google search to find the taxi fare, and the link came up on the first page).
And though I didn't find it as confrontational as the blogger (I only speak basic tourist Italian), I did end up taking the shuttle bus into town because I couldn't get an agreement on a fixed fare before getting into a cab, something I do everywhere there's a fixed fare to the airport.
This has never happened to me at FCO, and it was three years ago at Ciampino, so maybe it's gotten under control.
Btw, not so long ago taxi to Manhattan was an infamous pricing scam art JFK.