While the report does find fault in some research that he had supervised, Tessier-Lavigne is still one of the foremost experts in his field. This investigation is proof that academia is working as intended, as the indispensable tool of peer review helped uncover flaws in the research. While Tessier-Lavigne may have been lax in his lab, he isn't a fraudster and is showing his integrity by stepping down to avoid further distractions, despite being exonerated.
Data manipulation, especially manipulation of images, has become endemic in science. By manipulating data, researchers poison the well-being of science as others build on their fraudulent work. The stifling and cliquish world of academia can create environments where sloppy work is passed off and where it can be career suicide to question it. Tessier-Lavigne should have known better, as manipulation of data puts the entire scientific method in jeopardy.