Stayed out for more than 6 months

[sg678]

Hi. My dad who is 72 has citizenship interview soon.
In last 5 years, he has been out of USA for more than 6 months
in a year on 2 occassions. From the citizenship booklet
it seems that he may not be meeting the requirements.

On both occassions he was out for extended stay due
to health reasons. Does anybody have any experience
with this kind of situation..?? Will USCIS be willing to
accept this as a valid reason..??

Thanks