He should not have accepted the job if he wasn't happy with the SDE position in the first place. It would have saved Amazon and him money if he would have been upfront about what he wanted.
Hindsight is 20/20. The opportunity to make a FAANG salary, even if it requires putting in some time at the lower ranks, is not one to be turned down lightly.
The average computer engineering salary in Tel Aviv is somewhere around $85-95k, before (high) taxes, in a city which is the 9th most expensive city on the planet in cost of living, supposedly more expensive than New York. Level aside, $110k guaranteed, before lucrative RSUs, (I presume) lower taxes, lower cost of living... should speak for itself.