As discussed in How the mapped user changes your environment, mapping a service account to a Windows user makes the account vulnerable to attack. If the attack results in a guessed password, the attacker would be able to log on as the service account, and, potentially, impersonate the service account on multiple computers on the network using SSH keys. Because the mapped user is also a valid Windows account, a successful dictionary attack might also grant access to Windows computers on the network. If the attack did not result in a guessed password, the failed password attempts could lock out the service account, making it unusable.
For service accounts that do not have a password, this vulnerability to a password-guessing attack would be a new security risk that did not previously exist. Therefore, simple account mapping is typically not the best solution for service accounts that are secured using sudoers policies or SSH keys instead of an account password.
If simple account mapping is not the appropriate solution for the service accounts in your organization, you may want to consider creating one or more service account roles. Roles enable you to securely manage the privileges of UNIX service accounts through Active Directory.