Clearly, this is an error - the code in code library is submitted by users without any review and is not guaranteed to work.

Nevertheless, it *will* work most of the time. It may sound strange - but in fact, unless you have a defective EEPROM or some other problem with your hardware, there is no need to check for the presence of ACK; and as the SDA driver is open collector both in the microcontroller and the EEPROM, it does not matter whether only one of them drives it low or both.

JW