It doeasn't really have anything to do with sapience.
Picard never needed a proof of Exocomps' sapience. He promptly organized a meeting to discuss the possibility that Exocomps might be alive after one of them exhibited a self-preservation mechanism that involved feigning death/malfunction. The conclusion of the meeting was, if something is
alive it can't be exploited for work. Clearly, at least in Picard's eyes, this doesn't apply to exploitation for recreation (recxploitation

) and lifeforms large enough to bear the combined weight of Picard and his saddle

.