To be fair the complaint was how much they charged to put the bags in the hold, not the fact they had]
pwalhx is correct. I thought it was a very clever response to FR's attempt to influence free speech. The article would have been even better if they had compared the 'supplementary' costs on FR with another carrier on the same day, same route.
If Skyscanner is reading this - there's your new product idea! (Subject to my 10% commission plus 2.5% for credit card)