Anti-skid may be only be deemed inop due to inoperative required associated systems which can be shared between the anti-skid and other systems.
Thus when anti-skid is deemed inop its root cause may also affect proper functioning of other systems such as but not limited to automatic speedbrake deployment.
As it would take to many scenarios to be described, manual speedbrake deployment is taken into account when the anti-skid is deemed inop, as it could be an associated system such as the wheel spin up sensor or weigh on weels logic not functioning properly.