E Agbhinhu Bsisni, translated according to Rashi is: If he [the creditor] picked them up and put them in baskets they are his.
Why must they have been put into the basket? By lifting them did he not get possession and ownership?
According to Rashi, the Kinyan is actually the Hagbahah. However, there is no reason for the lender to have picked them up merely to be Koneh, since he did not suspect that the payment was imminent. The Gemara, rather, chose a stage in the usual process of harvesting dates which has a Kinyan.
D. Zupnik
In essence, the Malveh need not make a Kinyan at all for the entire duration of the loan, for he owns the produce. Therefore, the distinction of the Kinyan necessary before the repayment is not congruent with regular Kinyanim. Actually, even the ripe fruit should be his since they ripened before the repayment. However, the Chachamim classified the Kinyan Peros of Mashkanta to include only the produce which he had actually taken into his possession (this constitutes Achilas Peros), and therefore a standard Kinyan is insufficient.
D. Zupnik