"Niches" (fiscales) = tax breaks

"Rabot" is a plane (tool), reference to the language the government has put into circulation, according to which they are engaged in "planing down" ie reducing tax breaks.

But the slogan questions whether this "planing down" will be fairly done by the "nabot des riches", the rich people's dwarf ("nabot" = "nain" = dwarf), meaning...

Now who could that mean?