It seems clear enough to me that Grothendieck was (perhaps is) sui generis as a mathematician, something that can be said of a few other mathematicians in each of the 19th and 20th centuries (e.g. Ramanujan). There seems to be something in his approach that both leads others to hyperbole about him, and led him to apply hyperbole in his pronouncements on mathematics. Which is not an unmixed blessing: cf. Weil's comments in the preface to Basic Number Theory. This particular pronouncement seems less interesting than others. It is the type of thing that the Bourbaki group often said, and its only justification lies in the need to have some sort of heuristic in choosing a research area. The historical assessment seems to be that distribution theory had raised issues in TVS theory, and Grothendieck dealt with those