Composing a tribute to Noam Chomsky is painful, not for the writer, but for Noam. Whatever you write is bound to embarrass him. Calling him a genius will only make him wince. Offering thanks for having created a field of study that has turned your life into an intellectual adventure will only make him shake his head self-consciously. Thanking him for all the times he has turned your evanescent musings into a focused argument worth thinking about will only make him blush. Praising him for the clear-eyed way he has unmasked the hypocrisy of power will only make him want to change the subject.
Because you consider yourself fortunate to have had your timeline on this earth and his coincide and because you owe him more than any encomium can possibly do justice to, it is best to fall back on time-honored things. Raise your glass and wish your friend all the health and happiness there is.