In the context of penetration testing or cybersecurity, hiring a consultant with a background in unauthorized system access could present both risks and benefits. From a risk management perspective, Candidate 2's history of unauthorized system access is a significant red flag. Such past behavior indicates a willingness to operate outside of legal and ethical boundaries, which could pose a risk to the firm and its clients, especially in a role that requires trust and adherence to legal guidelines.

However, the very skills that enabled unauthorized access might also provide the firm with deep insights into hacker methodologies, potentially enhancing the firm's capability to secure systems against such intrusions. It is a common practice in the cybersecurity industry to employ individuals with a history of hacking in roles where they can contribute positively, known as "ethical hacking" or "white hat" roles.

Nonetheless, given the legal and ethical responsibilities inherent in cybersecurity work, Candidate 2's past criminal charge of unauthorized system access is the most pertinent to the role and poses the most direct risk to the firm's operations and reputation. It would be crucial for the firm to conduct a thorough risk assessment, including the nature of the unauthorized access, the candidate's subsequent actions, rehabilitation, and current capabilities, before making a hiring decision.

From the provided information, it appears that Candidate 2 should most likely be excluded from consideration due to the direct relevance of their criminal charges to the position in question. Without evidence of rehabilitation and a clear demonstration of ethical standards, the liability risks might outweigh the potential benefits to the firm.