Is the testament (Wasiyyah) of a person placed under protective custody due to foolishness (Safih) valid?

Primary text

The testament of a person placed under protective custody due to foolishness is valid, according to the measured opinion of Ahmad and the majority of scholars. The rationale is that such a person is rational, and therefore his testament is valid, similar to a rational minor whose testament is valid. Furthermore, his testament exclusively benefits him without causing harm, making it valid, just as his acts of worship are valid.