Does אביי hold חשיד אממונא חשיד אשבועתא? (Bava Metzia 6a)

This is a מח' הראשונים.

Rashi understands that אביי has a fundamental argument with ר' יוחנן and that אביי holds חשיד אממונא חשיד אשבועתא. He explains the Mishna that שמא יש לו עליו מלוה ישנה. The Rishonim explain according to Rashi that all the proofs that were brought are answered this way as well. In those cases also we say שמא יש לו עליו מלוה ישנה. If so why is הכופר בפקדון פסול? The Rishonim explain that when all we have is a suspicion that you stole something the claim of שמא יש לו עליו מלוה ישנה can take care of that. But by הכופר בפקדון where we know that you took money, then שמא יש לו עליו מלוה ישנה is not strong enough and we say חשיד אממונא חשיד אשבועתא.

The Ramban and the Ran offer an alternative pshat. They say that אביי agrees that we don't say חשיד אממונא חשיד אשבועתא. He only argues with ר' יוחנן on the reason for the שבועה in the Mishna. אביי says that the חכמים would not be מתקן a שבועה because we are worried about people attacking each other on the streets. We should not assume that people will just go ahead and attack people on the street and grab for no reason. Rather, the reason for the שבועה in the Mishna is because שמא יש לו מלוה ישנה and that is why he grabbed. However, in any case even if he is חשיד אממונא he is not חשיד אשבועתא and like all the proofs that the Gemara brought that חשיד אממונא לא חשיד אשבועתא.