Of the ways listed, which is the best way to temporarily suspend a user's ability to interactively login?

Changing the UID breaks file ownership across the filesystem because all files owned by the original UID become orphaned, making it destructive and inappropriate for a temporary suspension.

Changing the password is not ideal for a temporary suspension because the original password is lost and must be manually reset again when access needs to be restored.

Changing a user's login shell to /bin/false or /sbin/nologin immediately prevents interactive login because the shell exits with a non-zero status upon launch, denying the session. This is easily reversible by restoring the original shell entry in /etc/passwd without altering passwords, UIDs, or any other account data.

Removing the user's /etc/passwd entry permanently deletes the account definition from the system, which is a destructive action not suitable for a temporary suspension.