From the press release: "ISL's new Dynamic Auto-Release mode enhances algorithm transparency by intelligently adjusting recovery for low-frequency content. Unique channel linking visualizations and interdependency controls make ISL 2 an unprecedented solution for a new generation of production requirements."
True peak is not an absolute quantity since the number you get is dependent on the method employed to perform the calculation. The ITU recommended technique is to oversample the waveform 4X, but no one is beholden to that. It's just one way of synthesizing the number. Apple doesn't specify how they are making the calculation in afclip, and they could be doing something slightly different than ITU based calculators, like the Nugen module.
If you keep peak levels a couple of dB down from full scale as has been recommended then it is a moot point anyway, because -2 dBTP and -1.9 dBTP both well below full scale.