DY: Whoever wrote that answer will have a serious Din V’cheshbon to give for his unfounded and false attack on the Pachad Yitzchak, even if he didn’t mean it.
I always thought that P’shat in the Gemara is like he said, though (based on Rashi) that it is Nivra B’guf Ha’adam and therefore isn’t P’reh Ur’veh. That raises more questions, though, for example could you then kill a wasp inside a fruit that has never left the fruit, etc.? His second answer also is obviously wrong because based on that it should be Muttar to kill any bird on Shabbos (and a Par’ush as well, which is also false). His third answer is the common one from R’ Shlomo Zalman and the Michtav Mei’Eliyah.