In a case where piercing the bottom of the can will cause unwanted liquid to drain out, isn’t this a possible psik riesha de’nicha lei of boreir? In other words is it possible that the method of preventing a tikkun kli will result in a possible melacha de’oraita of boreir?
ב"ה Shalom The Shemirat Shabbat Kehilchata in two places (Chapter 3: 58, Chapter 9) ,one time in the case of opening a can on Shabbat and the other time in regard to using a noodle strainer on Shabbat not for the sake of staining the noodles but with intention of transferring the noodles. In both cases , He says there is no problem if some liquid may pours out since it does not make it "borer ". This is because the melacha is considered "pesik Reishey" only if the person actually is doing the melacha but expects the inevitable result not to happen. For example putting something in a strainer and expecting the liquid not to come out. However in this case he is opening a can in an indirect way in order to eat the contents not to drain the contents, therefore even if someone liquid spills it is not considered "borer". (See נשמת אדם יח:ב( All the best