What logic? He's making a factual assertion, not an argument. Unless you're suggesting accusations of criminal conduct don't require supporting evidence...
EDIT: Here's a link to the results of GitHub's independent investigation (by an external party): https://github.com/blog/1826-follow-up-to-the-investigation-...
We hired Rhoma Young, an independent, third-party investigator that GitHub had never worked with before. Rhoma has a long history of conducting fair and impartial investigations, with 30+ years of HR experience. She has worked with every type of organization, from Fortune 50 companies to local governments, and frequently testifies as an expert witness for both plaintiffs and defendants in depositions, arbitrations, and in litigation involving discrimination, harassment, retaliation, disability, and mitigation of damages...
...We gave Rhoma free rein to review all the media reports, public allegations, and HR records so she could create her own investigation and interview plan. She identified three key issues that she focused her investigation on: the claims about Tom and his wife, the claims about the male engineer, and the general culture and working environment at GitHub... The investigation found Tom Preston-Werner in his capacity as GitHub’s CEO acted inappropriately, including confrontational conduct, disregard of workplace complaints, insensitivity to the impact of his spouse's presence in the workplace, and failure to enforce an agreement that his spouse should not work in the office. There were also issues surrounding the solicitation of GitHub employees for non-GitHub business and the inappropriate handling of employee concerns regarding those solicitations...
...The investigation found no information to support misconduct or opportunistic behavior by the engineer against Julie or any other female employees in the workplace. Furthermore, there was no information found to support Julie’s allegation that the engineer maliciously deleted her code. The commit history, push log, and all issues and pull requests involving Julie and the accused engineer were reviewed. The investigation considered all possible commits surrounding the accusation of passive-aggressive code removal... After interviewing over 50 employees, former employees, and reviewing evidence, Rhoma found nothing to support a sexist or discriminatory environment at GitHub, and no information to suggest retaliation against Julie for making sex/gender harassment complaints.