I wonder if someone can help me with a gemara question? I’m revising the ninth perek of Bava Qama and on 96b the gemara explains a passage in the mishna in a way that strikes me as totally incongruous.
The mishna says, “זה הכלל כל הגזלנין משלמין כשעת הגזילה”: "This is the rule: all robbers must repay the stolen item as it was at the moment of robbery". The gemara asks what “זה כלל” is coming to include, and resolves that it’s including the case of a person who stole an infant animal, which grew up and became an adult while they owned it. As a result, they are not subject to the din of ארבעה וחמשה since they technically ‘acquired’ the animal with this shinui.
My problem is, the din of ארבעה וחמשה applies exclusively to theft, not robbery. Until now, all we’ve been speaking about in this entire perek is robbery (gezeilah). This whole mishna, in its entirety, is about gezeilah. Even this line explicitly refers to gazlanim! Why would the gemara now take it as referring to a case of theft (geneivah), such that we can apply the din of ארבעה וחמשה, which is inapplicable to robbery (gezeilah)?