Alan Hudson was a tremendous player for Chelsea and I do agree that players of flair were often under represented in England squads at that time. However, I don't agree with his analysis of the Grealish situation. What I gleaned from the Euros was that we had a very gelled squad with incredible team spirit, rather like Germany in 2014, that did carry us to a penalty shootout in the final game of the tournament.
I'm also not sure of the FA's responsibility toward Hudson. He was not their employee and whilst it's sad that he is still suffering from the effects of injuries sustained outside of football, albeit through no fault of his own, I'm not sure what they could do to help him without also addressing the problems of every other former player with long term injuries or declining health.
I may be wrong but my first reaction is that he should perhaps address his concerns to CFC.