This statement is related to a defined process (Generic Goal 3), not a managed process (Generic Goal 2). A managed process (GG2) refers to processes that are planned, executed in accordance with policy, involve relevant stakeholders, are monitored and controlled, and are reviewed for adherence. Tailoring from the organisation's set of standard processes applies to a defined process, which is established under GG3.
Reference:
"Tailoring of processes from the organisation's standard processes falls under the scope of a defined process, associated with GG3".