The FT data objections are far from the strongest objections to Pinketty's work. Here are a few criticisms seem much more serious than nitpicking the data:
In brief, his theoretical mechanisms that supposedly predict and explain greater wealth accumulation are actually unsound, and if anything this seems to be the evolving consensus among economists who study the area.
It is even harder when there is an ideological block. In the first case, you get stonewalled, and ultimately ignored. In the case of ideology, you get shouted down, mobbed, and subject to various preemptive attacks intended to discredit and demoralize you before you even get to make your case.