A person does not wish to accept an invitation and publishes a generic sentence hoping it will be understood. I propose a direct and respectful response, if the situation is safe.
In the example, communicating unavailability prevents the recipient from having to reconstruct clues. It is not necessary to offer personal details to legitimize the refusal.
If pressure or fear exists, support may be needed. The right to choose does not depend on the ability to compose an allusion convincing enough for the audience.