If I were a strong player who had gotten strong with little or no help from the AGA, someone would have to do a lot of fast talking to persuade me that a tap is fair.
He may have got strong with little help from the AGA, but he probably wouldn't have got the invitation without the infrastructure of the AGA or the selfless work of AGA officials, so such a levy seems eminently fair. The only question is the size of the levy. In China it would be 25% (and I think income tax levels are even lower than in the USA), but it's possibly a case of gaol if you don't pay the levy there, and I think a recalcitrant US player could usefully be offered the same alternative. Or send him to Coventry, as happened with Yi Se-tol.
(Partial explanation: our UK newspapers have been full of articles on the US supercop who wants to head London's police force. He was famous for claiming zero tolerance works - maybe it does.)