Dear Yaacov,

Hello there and thanks for your question. Rashi in Bava Kama actually suggests two explanations. One is that he has Da'as as you mentioned, and the second explanation which can fit with his explanation in Shabbos. Perhaps this is what the Gilyon ha'Shas meant when he referred to Rashi's explanation in Shabbos. As a rule, throughout Shas Rashi does not always give identical explanations to similar terms or even sugyos. It could be that Rashi had two explanations and in Shabbos chose the one that fit best there, and in Bava Kama chose the one that fit best here.

Kol tuv

Y. Landy