In the table, all the particles except the electron and positron (and the proton-antiproton) are particles which decay. The decay rates allow the calculation of the lifetime of these particles and that is what is shown on the last column. Note that the electron and positron have a reference (1), which you have not copied for us, and the link you give is not from the publication itself, just for the image.
(1) must be pointing out that the rest of the numbers are lifetimes derived from experiments measuring the decays of the particles, but for the electron and positron this must be the lower lifetime limit from experiment . The limits are entirely due to experimental and calculational errors, not to the lifetime, if there is one; the number says that the electron is stable within experimental errors.
Within the standard model, the lifetimes of antiparticles are the same as for particles, and this has been checked by experiment.
But even if one could have a corresponding experiment for positrons the experimental errors would say nothing about the axiomatic symmetry on lifetimes between electron and positron. The experiments for the positron would be different and much more difficult to perform so the experimental errors would be different, but this would be irrelevant for testing the standard model axiomatic assumptions.
The same is true for what is given on the right for the proton antiproton, that might decay as some models predict. It is the proton whose lifetime can be checked very accurately. Antiprotons carry the problems of production and easy annihilation in any experimental setup.