No. If Steve is ultimately hired, his selection could be open to legal challenge by an unsuccessful applicant because your organization’s policy, which prohibits the review of unsolicited resumes, was not followed consistently.
Disparate treatment, a form of discrimination, cannot be avoided unless selection procedures are followed consistently—for every hiring decision and for every applicant. To help ensure consideration of all potential candidates, encourage your friend to submit his resume once the position becomes available, using the regular channels for submission.
Source: CCH HR How to: Recruiting and Hiring.