Is it permissible to marry a Saudi man and move to live in Saudi Arabia, while giving up (Israeli) citizenship and the consequent difficulty of seeing one's family, and is this considered a severance of the ties of kinship?

There is no blame upon you for marrying this man, even if it results in you being prevented from entering your country. Filial piety and maintaining ties of kinship do not depend on residing in the same country. Rather, they are achieved by whatever a person is capable of doing that custom considers to be a form of connection. And kinship has degrees, the lowest of which is abandoning estrangement.