Once an authoritative imperative establishes obligation, the accountable person may comply or violate the duty, but omission without justification carries legal consequences. Capacity to choose does not invalidate the obligation: it makes obedience and disobedience meaningful.
For an act whose compulsory status has been established, unjustified omission may be culpable. For a recommended act, omission does not carry that same consequence. The levels of legal demand must remain separate.
“Obligatory” therefore does not mean that a person is physically incapable of failing to act. It means that sacred law imposes a duty which can be violated and may attract accountability.
Being able to perform an act and being required to perform it are distinct propositions.