Also, dmesg reports that thinkpad_acpi's backlight controls are not enabled, so it is certainly not controlling the backlight in the VT:
thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver
thinkpad_acpi: Standard ACPI backlight interface available, not loading native one.
Also, dmesg reports that thinkpad_acpi's backlight controls are not enabled, so it is certainly not controlling the backlight in the VT:
thinkpad_acpi: This ThinkPad has standard ACPI backlight brightness control, supported by the ACPI video driver
thinkpad_acpi: Standard ACPI backlight interface available, not loading native one.