Shalom Eli,

Theoretically, the Shomer could have made a false Shevuah that the animal was "Shevurah," thus exempting himself from payment. Since he did not choose to do so, and rather is willing to pay the Keren, therefore the owner is willing to grant to the Shomer the rights to collect the Kefel.

It sounds like you are bothered by the fact that the Shomer could not have actually succeeded in claiming "Shevurah," because of the simple fact that there's no evidence to prove this, for example the animal's dead body. But frankly if we're considering the hypothetical possibility that the Shomer is willing to lie about how the animal died, then we can also assume he would be willing to lie about the whereabouts of the body.

Warmest regards,

Yishai Rasowsky

Shalom Eli,

I came across an issue that looks very closely related to your fascinating discussion, and so I wanted to share it with you. The Mefarshim on this Gemara consider the case in which there are Edim who can testify that the animal was in fact stolen, as the Shomer Sachar claimed. In that case, practically, the Shomer does not actually have the alternative claim of "Shevurah". The question is, would the Shomer be entitled to collect the Kefel in such a case? The Ritva and others say no; since the Edim make it impossible for the Shomer to exempt himself by lying, therefore we assume that the Makfid is not willing to grant the Shomer the Zechus to the Kefel. The Rashba, on the other hand, argues and instead maintains that even in such a case we should assume that the Mafkid at the outset intends to grant to such a Shomer the right to collect the Kefel, the rationale being: theoretically there was a possibility of the Shomer being Patur, had there hypothetically been no Edim on the Gneivah, and at the end of the day this Shomer is willing to pay and doesn't force the Mafkid to drag him to Beis Din to extract the money.

Warmest regards,

Yishai Rasowsky